Am I allowed to agree with my friends that my wife is fat
Do you really think that?
I'm the only friend who didn't say she's fat, so I'm about to tell her that she's fat just to be in agreement with them.
It's gross to insult your wife like that. You should always be supportive of her.
I'm being supportive by letting her know she's gotten fat.
That's insulting not supportive. You're really just trying to impress your friends by insulting your wife. This behavior will deeply hurt your wife.