As obvious as this sounds, this is not true for every couple! Common interests help couples enjoy spending time together, but are not essential. If you lack common interests, don't panic. The way you communicate together is more important than sharing interests together. 

By this, I mean each person feels heard and understood (at least to some level) when you talk to each other. I very much rate regular talking time together and using active listen skills. My ebook, "How To Listen To Your Partner So That He Or She Feels Fully Understood" explains this in more detail. 

Arguments (in themselves) are not good or bad for relationships. However, if arguments get out of control, or result in any abuse or violence, this is always bad for a relationship. Good couples argue respectfully! 

It is hard for couples to maintain a good relationship together without others. Times will always get tough, and in the tough times it is good to be able to turn to people who support the relationship to help get things back on track. Usually this is friends or family, but relationship counsellors can also help here! 

Spending time alone as a couple (especially if you have children) is vital for all couples. What is quality time? Basically it is time when you are alone together and connect with each other. Beach walks, coffees, playing board games all count as quality time. How much quality time do you need? Research suggest 2 hours a week minimum! 

When I ask couples what their "love languages" are, almost all men say touch is one of their top two love languages. Some women do too. Happy couples usually touch each other a lot. They hug or kiss when they get home from work, they touch on the couch watching TV, they cuddle in bed at night. These acts of touch help keep the relationship strong. 

Although I wish this went without saying, trust is synonymous with a good relationship. Any jealousy or mistrust (earned or not) can quickly destroy a good relationship. If you or your partner is experiencing issues of mistrust, get help immediately! 

It is hard for couples to maintain a good relationship if there is not outside interests that each person can bring to the relationship. You both should have your own friends, interests and hobbies! Often this is harder when you have young children, but be sure to arrange the parenting so that both people have time to pursue life outside of home (and work!). 

Research indicates that couples that thrive have roughly 20 positive interactions for every negative interaction. This means that for every thing you criticize your partner about, you should praise him or her for 20 other things. It is hard to do this if you do not fully respect and support your partner. If your ratio is a bit off, make sure you repair this as soon as possible! 

You and your partner are a team! This means that you share the relationship work. This includes housework, cooking dinners, doing jobs outside the house etc. Of course, not everything needs to be shared equally, but there needs to be negotiation about how these tasks are done. 

Without a good sex life, couples run the risk of falling into flatmate or friend relationships. One of the keys to a good sex life is the ability to talk about sex. If you and your partner have done this and still find issues sexually, seek professional help as soon as possible! 

Couples that work together on shared goals are more likely to stick together! Do you and your partner have relationship goals for the next year? The next 5 years? How about the next decade? If not, think about sitting down and discussing what you want together in the future. As with everything, the more you plan it, the more likely it is to happen!