Just some thoughts, with no mention at all of lesbianism. <Damn!>
So what do we really know about the 3 J's? Well we know:
1- They're on the football team. 2- They not very smart. 3- They seem to hang about together a lot. 4- They're obsessive about Quinn.
Number 4 is _wrong_. And I believe I can give a plausible explanation for that being so.
Basically we have 3 sporty, non too bright guys who above all are certainly very competitive. You know the type, if they where going to a movie and one decided for no reason to sprint to the cinema entrance from the car park then the others are guaranteed to run after in order to get there first. You or I would wonder 'why's he running?', then think 'who cares!'.
It's much the same with Quinn. None of them are really that bothered about her, but they'd be very bothered by one of the other two 'beating' them and going steady with her. If a Quinn-2 showed up in the school they might well transfer their attentions to her en-masse as it's the competition that's important, not it's focus. If Quinn picked out one to date the other two would disappear and even the 'winner' would lose interest in her very quickly
Quinn of course knows this perfectly well (she encourages it) even though they don't (they are dense). Each probably thinks only the other two really feel strongly about her.