I'm happy he's happy but sometimes I can't help to feel just a little jealous.
Most Helpful Guy
It's completely normal, so don't worry too much about it. Of course you should try your best not to let it affect your friendship, but you should accept those feelings and allow yourself to feel them. Talk to your ex about these feelings from time to time if you can (it depends on how close you are and how mature he can be about it) or find others close to you who can help you deal with them.