According to research, the number one cause of the breakup of romantic relationships is failure to communicate. If your relationship was otherwise happy, this problem can often be fixed by setting clear expectations and openly discussing frustrations before things explode in a big fight. Other issues can be harder to overcome, like infidelity or jealousy; but with work and counseling, even these types of issues are possible to work through.
The amount of sex that a couple has will generally decrease over time, but if the sexual attraction, respect and love are deepened, the couple will still want to be intimate. Even if sex only happens once a week, the couple still feels good about it and wants to do it. Outside of sex, the couple will enjoy hugging, giving each other a kiss or lovingly looking into one another’s eyes for a second or two.
It's important to not just talk, but to listen and hear what your partner has to say about what's going on in your relationship. You can show you're listening by summarizing what your partner has to say to show you've understood what he or she has said. You can also ask questions that show you've heard what the person has said and that you want to know more.