It's a myth that well-matched couples have equally well-matched libidos, says Kimberly Hershenson, LCSW and couples therapist.

And even if you were in sync the day you got married, kids, stress, illness, and other life events have a way of changing things.

This means it's inevitable you'll have disagreements about sex.

"There are other ways to feel connected if sex isn't happening as frequently as someone would like," she says.

"Physical intimacy is obviously important in a marriage but many of my clients don’t realise the importance of having an emotional connection to their partner first."

Once you are working as a team, you can troubleshoot bedroom strategies together.

Modern technology has lead to some uniquely modern relationship fights, especially when it comes to social media.

"These days we see a lot of 'cyber-straying' which means sneakily looking up and even reconnecting with old flames, despite being with someone else," says Wendy L. Patrick, JD, PhD, behavioral expert and author of Red Flags.

Then, when the partner inevitably finds out, they feel hurt and betrayed, she adds. The fix to this fight? Squelch that curiosity.

"Curiosity compromises trust and secrets are relationship saboteurs," she says. "Ex-relationships are in the past for a reason."

If you do want to maintain a connection with an ex, make sure your partner is in on all communications. 

Smartphones and tablets are awesome but they are also a huge distraction, ready to interrupt your precious time with your partner at any second, Patrick says.

Think checking a text or answering a quick email is not a big deal? Imagine if it was an actual person grabbing your attention every time a notification goes off. They'd quickly be the most annoying person in the room, right? So it's understandable how phones can become a major source of fights, she says.

The solution is simple: Put away your phones and decide on tech rules you can both follow.

"The impersonal nature of this communication often builds barriers, not bridges," she explains.

"Remember, your partner is your lifeline. Uplifting, encouraging conversations infused with real emotion will revitalise your relationship in a way that no amount of emoticons could ever do."

Couples have been fighting over chores, well, since chores were invented. This is because it's not really about who washes dishes or vacuums more, it's really about feeling like things are fair, says Fran Walfish, PhD., a relationship psychotherapist, author, and consultant on The Doctors TV show.

"What you need to realise is there is no such thing as a 50-50 split of responsibility in a great marriage. There will be times each of you will have to give 100 percent," she explains.

"Great couples learn to sacrifice willingly for one another without expecting something in return." Easier said than done, right?

"Cultivate this mentality by finding little ways to serve your spouse every day," she adds.

Call it the lesson of your freshman college roommate: Live with someone long enough and you will find something about them that drives you absolutely insane.

In long-term relationships, those little annoyances can fester into full-on warfare, especially if you use these quirks to intentionally trigger each other.

"This is totally normal, even with the people we love the most," Walfish says.

"Instead of creating a mental list of all the things your partner does that annoy you, try and put them in perspective and make a list of all the things they do well. Then extend grace for minor annoyances, knowing that your partner likely does the same for you."

Just like your partner has little habits that drive you nuts, they also likely have aspects of their personality that you wish were different.

In the beginning of your relationship, it's easy to brush them off as cute quirks with the expectation you can change your partner later… and this is how you start a never-ending fight, says Rhonda Milrad, LCSW, a licensed therapist and founder of Relationup.

"You complain and even overtly show your disdain, hoping that this will get your partner to change, however it only makes the problem worse," she explains.

"Instead, learn how to accept and even find ways to appreciate the idiosyncrasies in your beloved."

Fighting over someone’s motives for staying in the relationship and even dropping the "D" word is surprisingly common, even in happy marriages, says Rabbi Shlomo Slatkin, licensed clinical professional counsellor and co-founder of The Marriage Restoration Project.

The problem with this argument isn't that you're fighting, it's that you automatically assume that fighting means divorce.

"The truth is that all couples argue," he says. "Instead of wondering if you made the wrong choice, remember all the reasons you thought this person was the right choice - you will find that you’ve picked someone who will uniquely challenge you but will also help you achieve ultimate personal growth and healing." 

Just because two people are in a stable relationship doesn't mean they stop growing and changing - but it can be all too easy for couples to miss these milestones when they’re focused on kids, work, and all the other minutiae of daily life.

This can lead to some very frustrating (but very normal) blowups, says Lesli Doares, couples' consultant and coach, author and host of Happily Ever After is Just the Beginning.

"When we first meet and get married, there is a lot of conversation and sharing about who we each are but as the years go by, we think we know each other and continue to act as if neither has changed," she says.

"The way to fix this fight is to keep asking each other questions and don't assume you know the answers."

Humans have an innate desire for equality and fairness so if you feel like you're consistently getting the short end of the stick, it can lead to major resentment and spark a serious argument.

But scorecards are for golf, not relationships, so stop tallying up everything you do and comparing it to your spouse, Doares says.

"If one of you isn't happy with the way things are going, the relationship cannot be happy and the way to stop this argument is to make decisions together," she says.

"Learning how to reach an agreement that you both can support and implement is critical."

Is there any worse feeling than feeling like the (unpaid) maid, chauffeur, mechanic, nanny, or chef? Being taken for granted is a major - and understandable - source of fights between couples, says Allen W. Barton, PhD, a research scientist at the University of Georgia’s Centre for Family Research and founder of LiveYourVows.

Thankfully the solution is as simple as these two little words: Thank you.

"It’s such a simple thing that it often gets overlooked but expressing appreciation to your partner for things they have done for the relationship and family is key to stopping contention," he says.

"Make it a practice to thank your spouse every day for something."

The short answer to this question is usually "yes".

It’s not because we necessarily want to lie to our partners or that we’re inherently dishonest but rather that we think telling little white lies, or withholding the truth, will prevent a huge fight.

Unfortunately, people can often tell when you're being less than truthful and the fight soon becomes about that.

"Based on my research we’ve found that many people tell white lies to their partner and while the majority of people say that white lies are not okay they still find excuses to say them," says Jason B. Whiting, Ph.D, LMFT, professor of marriage and family therapy at Texas Tech University and author of Love Me True: Overcoming the Surprising Ways We Deceive in Relationships. 

The antidote? Honesty.

"Telling the truth, even if it's hard in the moment, will strengthen trust and make you closer in the long run," he says.

The silent treatment - rare is the couple that hasn't had this fight-pretending-not-to-be-a-fight. But even though you're not yelling at each other, or even saying a harsh word, this fight can be just as damaging.

This is because the silent treatment allows resentments to build and fester, says Erika Boissiere, licensed marriage and family therapist and founder of The Relationship Institute of San Francisco. 

"Silence is a wedge that will drive more distance between you the longer it goes on," she says.

"If you need something from your partner, you must request it. Your partner cannot mind-read your unspoken expectations. It is your job to ask for what you need in a kind, compassionate way."

It’s normal to look for patterns in behaviour, it can help you learn what to expect from others, yet constantly bringing up past mistakes is a sore spot for many couples.

How do you decide when to forgive and forget and when it's important to remember?

"You can't expect that when one person does something reckless, threatening, or destructive that their partner will just get over it," says Wendy Brown, clinical member of the Ontario Society of Psychotherapists and author of Why Love Succeeds.

"Their worries, trauma, and concerns must be addressed before you can move on."

This doesn't mean that this fight has to be an endless round robin of accusation, hurt, apology, and resentment though.

"You need to look for ways to openly discuss the past in a calm way—a therapist can be an impartial third party to help you do this," she says.

Written by Charlotte Hilton Andersen. This article first appeared in Reader’s Digest. For more of what you love from the world’s best-loved magazine, here’s our best subscription offer.