This is the one thing I dislike most about GGGB. By having a boyfriend in the beginning, you need to choose: be loyal, break up or make him a cuck.
Not having a boyfriend in the beginning and/or starting the game as a virgin would give a lot more agency and possibilities.
Absolutely. And those things can be done through implicit choices really easily, like through a flashback scene, where she's recalling her life up to that point and the options show up as her story advances. Something like:
"And this is Bob... we met when we were kids and became great friends as we walked to school together every day. And then, a few years ago..."
Option 1: "We started dating" - Normal boyfriend path.
Option 2: "He was too shy, so I asked him out" - Meek boyfriend path, virgin MC.
Option 3: "He came out of the closet" - Bob is a gay friend path, virgin MC.
Option 4: "I started dating someone else" - MC single (she broke up after a while), not virgin and not dating path.
but I think Eric is actually a decent guy and cucking him kind of hurts.
I think the opposite, actually, Eric would be a great person if he was a real, but that just makes cucking him even more fun.
If I was to describe an ideal path on GGGB for me, it would be one where they're childhood friends turned couple but haven't done anything beyond holding hands or shy kisses on the cheek.
Then the MC cheats on him behind his back without ever revealing it, always coming up with absurd explanations for weird happenings - when caught with cum on her face, she says it's a skincare product, she pretends to drop something under the table and uses that opportunity to suck a cock, she gets a QOS tattoo and says that it's because she really loves poker, then she gets pregnant and claims it happened because he jerked off using her panties, that kind of obviously-cheating-but-not-for-sure scenario.
The bull would have to be either the gang guy who can dance with her(and more) during the first visit to the club(and you can join his gang after) or someone just as despicable.
I'm really fond of NTR in its more "cruel" forms, but it doesn't fit every game since that is as evil as it is silly and not believable at all.