Is having an erection good or bad when grinding with a girl?

ok so i just had my junior prom and it started off great. we were grinding alot and i got an erection(kind of the first time i was really grinding with a girl). it seemed like she liked it because she started pushing up against me more. everything was going good and i thought it was ok to get an erection whenever i grinded with her. so then everything went good until the last hour. she started pushing up against me less(WITH ERECTION) then 2 times she suddenly stopped and said she was thirsty or had to go to the bathroom.(this girl always dances by the way. then me her and 2 other people were talking together and her friend(A GIRL) called her up to dance. i went to go with her and then she kinda waved me away and said she would be right back. after that she seemed a little weird and we didnt dance at all for the rest. im just really confused because i dont know how it went so good for most of the time then just bad the last hour.....please answer honestly and i appreciate both guys and girls to answer....thanks!Is having an erection good or bad when grinding with a girl?
It is not a bad thing. It is pretty natural for a healthy guy to get exited when a girl is rubbing her but up against your crotch. It lets her know you think she is sexy, as long as you are not purposely shoving it into her while you dance.

She enjoyed it and was getting turned on by it, but then she realized things were moving too fast and she wasn't ready for anything sexual to happen. She danced with her girlfriend for support, and was asking her for advice on the situation.

If you really like her tell her that you were exited because you like her and she is a sexy woman, but that doesn't mean that is the only thing about her you are interested in. Tell her you'd like to go out with her again, and pick somewhere safe where sex won't be an issue like a restaurant or a movie. Find out how she feels about what happened and tell her how you feel about it.Is having an erection good or bad when grinding with a girl?
I think it's hot when a guy gets an erection while we are grinding.. I love it!!
well, i think she felt like she was gettn wet so she had to take care of that. congrats ur a man