What happens in the bedroom at nupital night?

Whatever you want! If you aren't up for any kind of sexual romance, then nothing but sleep, but if you are then anything can happen.

Most important thing is to talk to your partner about what they expect to happen that night before the night arrives.

If they aren't willing to talk about it then you might want to wait on getting married. Because sex is a big part of a marriage, and you need to talk about all your problems before you get married.