Steve the day after he found out you cheated on him with Bucky.
He was so angry at the both of you, that he just punched the boxing-bag harder and harder until he punched so hard, that it would fly away.
"Rogers, calm down. You'll get over it. You'll find someone way better than (y/n)."
Tony tried to assure him.
"I DON'T want to get over it, I DON'T want to find someone new. I LOVE (y/n) and everything is going to be just fine. I just need to get off some steam. If you could leave it would already be a lot of steam less."
Tony didn't hesitate and left immediately, he only was there because Fury asked him to try and calm Steve down.
[this one's really bad, sorry]