What makes loving couples lose interest in each other?

Now in days couples think that they are going to live together forever, or they will last forever. You can see them planning how they want to spend their life together but, once they are marriedthings change a lot. The couple that once we saw happy and smiley we suddenly see fighting and arguing. A marriage that does not have communication, mutual interests or common understandings doesn’t workat all.
Bad communication is the major problem that makes loving couples loses interest. First of all when there is a problem, the couple should talk about it and try to solve it. For example ifthe woman thinks that her husband is cheating on her , she talks to him and tell him what she feels so the two can deal with it. Also the communication makes the couple feel free. Once they have talkedabout suspicion of cheating both the wife and the husband are going to feel more comfortable. Finally a big feeling occurs when you keep everything to yourself and you don’t tell your partner, it iscall rancour. When you keep everything to yourself, for example if you don’t like how your partner is acting or doing something and you do not tell him about it and you just keep it for yourself, hewill never know why you are feeling that bad and he won’t do anything to change it, and things will keep growing bad. Just because of the bad communication couples can stop feeling the same afteryears of marriage.
Another cause of losing the interest in the partner would be the change of interest. The principal thing is when you get bored of the same routine that you have with your partner.Doing the same things over and over, like a way of life it it always takes you to a point where get tired of it. For example if the woman treats the man the same way, he at a point will get tired of it,and will want another way to be treated. Secondly, when you are getting closer to your couple you think that everything you think is going to be real. But expectations can make you fail in love...