It sounds like you're still very early in the game, Eric leaves roughly 1/3 of the way through the game and you can tell him you won't wait for him. It's incredibly well sign posted, literally cannot miss it. You also cannot break up with him without losing good points or gaining bad points in some fashion before he leaves. I'd tell you what happens and why, but you already mentioned not looking ahead in the walkthrough for spoilers.idk it might be bugged? cuz i had "mad at him" yet he still offered to go to his place...so now im gonna loos more good points by turning him down....
So my advice to you is play the game the first time, really two times, just going with your gut feeling on how you would want to play and then come back to it trying to get certain outcomes. If you want a very specific outcome, but also don't want spoilers then there isn't much we can do to help you. Generally it's pretty much impossible to not gain some bad karma and loose some good karma going for anything other than a loyal girlfriend to Eric route. So I'd also recommend not getting too caught up in the karma system.