Not completely sure. I heard somewhere that love only lasts for about 2 years. I guess that would be the infatuation finally ending. I think that love is real though. Married couples may fall out of infatuation with each other after being around each other all the time but I think that it changes into a new love eventually. Like the kind of love that you have for your family. You really love them, and you couldn't do without them. Sure, you might not get that feeling of butterflies in your stomach every time you see them anymore, but they are now your family and you value them above all else. It also depends on the people because some people just aren't suited to being in a relationship in which there is no infatuation left and they are the type that may stick around for a few years, then divorce and leave to find the next person that they are infatuated with. Also depends on whether or not you can put up with their usual personality and their habits and lifestyle around the house I.E if one spouse leaves trash everywhere and farts and burps while scratching their ass and then proceeded to touch all the food in the house as well as the spouse with that defiled hand while the other spouse is big on cleanliness and maybe even OCD that is just a terrible combination that is destined to fail. And OP, not all people marry for sex. There are plenty of couples that marry just from the infatuation so I wouldn't include marriage under "and excuse for people to have sex". And that doesn't make any sense anyways because people can have sex regardless of whether they are married or not and if they were only in it for the sex, then they would just be fuck-buddies and screw all the time without any real feelings for each other. Some people also marry in hopes of one day making a family of their own with kids and watching them grow up. And if love really didn't exist at all, then I think that people would just divorce each other when they get older and they don't look as beautiful as they used to because they would be very shallow. If no one was committed enough to stay with a spouse out of love, then I don't think that there would be marriage in this day and age. Just because you feel like love doesn't exist for you personally, or with the people around you and their relationships, it doesn't mean that there is no love. It just means that you are looking in the wrong places.