not all, but many NTs tend to see that (post-"victory" happiness) as smugness or gloating, etc.

it's not wrong to enjoy or to be optimistic for the other person, but they may sometimes feel that they've been defeated and which is often considered intrinsically a bad thing, or as a type of unwarranted aggression. so positivity after that can be interpreted as bad manners, cruelty, rudeness, any number of negative things.

all I'm saying is, it pays to proceed cautiously if you value the relationship.