1. Bucky and Tony are together and not hiding it but the avengers are clueless and think that they hate each other but Bucky and Tony just like to argue. I this that Tony at some point said "it's not our fault that you don't stay for cuddles afterwards" or sth like that.
2. Bucky had enought of Team Cap talking shit about Tony and he explode at them and starts saying how amazing Tony is while he's standing behind Bucky (he doesn't know that Tony is there)