many guys feel that any type of emotional outpouring of that kind is a weakness
Pop raised me hardcore macho Irish. I so completely subliminated my feelings I couldn't even tell you what I felt, just what I thought.
I got lucky by dating a psychiatric nurse from Manhattan. She mention I lacked "affect". (WTF is affect???) She added that as my GF she shouldn't also be my psychologist and that if I was curious about it I could speak to someone at the psych unit at the local hospital. I did. They laughed. Actually they almost rolled on the floor laughing.
I asked how I might fix this and spent two years in group therapy (lots of people of both sexes have some issues with emotional denial and the boyfriend mentioned might too. It was a good investment reacquainting myself with my feelings. I feel complete now and have insights I'd have never guessed at.
Let me add that while this may affect the BF it's usually more a case of deception that brings couples to question eachother's motives.