Every time I kiss someone I like I feel guilty or bad right after

Hey, I am 18teen I only have been in one serious relationship and it was pretty bad one. anyways the first time I kissed my ex boyfriend I felt bad, I felt Ike I was doing something bad because we weren’t dating at the time, that ended like 6 months ago. Yesterday I went out with this boy on a second date and we kissed and on the second kiss I was feeling and thinking “this is bad” “I am doing something evil” idk why this happens to me… and if I kiss a random dude drunk I just don’t care about it HELP