It's not a matter of staying faithful. He's already said that he'd never cheat.
The way I see it, you're bored. It's sounds harsh, I know, but trust me when I say everyone's been there in one form of relationship or another. Whether it's a friendship, GF&BF thing, Married Couple, Friends-with-benefits, any of them.
And here's the thing, you don't need to lie, or make yourself hate her, or make her hate you, or anything like that. You just need to tell her how you feel. Straight up honesty.
Forget about her depression, if you're honest and upfront she'll be fine. She's supposed to be someone that you care for and she's supposed to care about you, right? You're supposedly a happy couple? (I'm assuming) You get on fairly well? You've been able to tell her your feelings in the past? (Of course you have, how else are you together?)
So just by those facts alone, you should be able to sit down with her and talk this out. Who knows, maybe you'll re-ignite something within your relationship? And if not, you've done all you can do, honestly and in the least douche-eist way going.
Most relationships screw up because of a
lack of communication. Mo'Fokin'
FACT! I've seen and experienced it more than enough times. And 7 times out of 10, it's the guys that screw it up. Girls, more often than not, plod along in their relationship quite content to voice how they feel to the guy and guys drag behind but don't say anything. (Why do we do this??) And because the guy never talks about anything, the girl doesn't really ask. Or if she does, she'll ask all the time. And the guy refuses to say anything or bottles it up. This leads the guy into becoming bored because he thinks either, the girl doesn't pay much attention to him...or he's becoming annoyed with her constantly asking him about his feelings and stuff. And Ta-Da! Before you know it, he's cheated. Cue a Shitstorm.
You can prevent this. Just sit her down, tell her how you feel about the relationship, be open to suggestions on how to fix it. And if it comes to the point where you absolutely
have to break it off with her, then do it. Don't pussyfoot about, this is someones life you're playing with, remember that.
If it all goes well in terms of ending it, wait a little before talking to the other girl about your feelings. Have some respect for the relationship you've just come out of and the girl you shared it with. That way, your ex won't hate you and your group of friends won't see you as a bad guy. What have you done wrong? You've stopped a relationship that you weren't fully committed to anymore. No one can say a bad thing about that.
In situations like this, if you commit yourself with a little bit of self-dignity, honour and honesty, people
will remember it.
Good luck with whatever decision you make.
