system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why do couples so often experience a decrease in sex drive shortly after marriage?
gpt
There isn't one good answer for that because for one, it isn't the same with each couple and two because it doesn't necessarily always happen. 

One common reason though is simply time. A married couple will most likely spend their days working and by the time the day is done, sleep sounds like a much better idea than sex. 

Another reason is that after a while, a couple's sex life tends to become a little bit boring. When you first start having sex, you're both willing to try different positions and other stuff to please yourself and your partner. After a while, you figure out what works and it becomes more relaxed and not as exciting. 

Third, as you get older, your libido drops simply because that's how your body works.

But really, tons of married couples still have plenty of sex drive, but they often have to actively "spice things up" to keep their libidos up and continue to make sex exciting.