I don’t want to include friendships after bouts or rivalries since that’s pretty common, but what were some bouts between two fighters that were actually pretty good friends?
Ali vs. Ellis. Both had grown up together, fought together as amateurs, sparred together, and finally fought in 1971. They were closer friends and the fight turned out to be rather pitiful. You could tell that Ali wasn't really trying hard to knock Ellis out. Also, Hasim Rahman and Monte Barrett put up a miserable performance against one another cuz they were friends and supposedly didn't want to hurt one another. Thirdly, I remember when I watched Griffith-Tiger II, that Griffith commented that he and Tiger were very good friends.
The rule in HEMA, is that you take it easy on your enemies, and batter your friends three feet into the ground!
Joe Louis and John Henry Lewis were pretty close outside of the ring, to the point where Louis was only willing to give John Henry a Heavyweight title shot if he promised that he'd retire afterwards. Louis know that John Henry's health was deteriorating and that he could use that final big pay day before calling it quits. Louis went out there and finished it as quickly as possible, and John Henry eventually kept his end of the bargain by never fighting again, albeit he tried to renege on his promise to Louis.
Evander Holyfield and Henry Tillman were great friends from the 1984 Olympics and, in 1987, Evander was best man at Henry's wedding. That same year, Evander knocked him out and absolutely beat the sh1te out of him. With friends like that, who needs enemas? See what I did there?
Frazier and Foster was said to be Great friends. It didn't stop Frazier from damn near killing Foster.
I'd guess that boxing is a pretty small industry once you get inside. So I'd think a lot of people - fighters, trainers, officials, managers, promoters - probably know each other pretty well and have developed friendships.