Possibly he's just curious but the point is that he's curious about a man. Agree with Donny here and most likely Erica too. That's not what he wants- it's about the man. That has nothing to do with whether or not his current GF gives good and/or frequent blow jobs- if it were, perhaps he'd have joined an online hookup site seeking women to blow him. But this is a dude that joined an online site specifically to look for oral sex from other dudes- so the situation here is that he's seeking a man. I can see a scenario in which a straight man who would rather seek a good and/or frequent blow jobs from skilled women would get frustrated and take it instead from a gay/bi man since it's easier and if he found himself in a situation where a guy was more than willing to suck his cock, I can see a 'why not' attitude. If it were a matter of the quality / quantity of blow jobs, he would not be out seeking it online from men specifically.
