Wait, so you guys are both dating the same girl, but keeping it from each other? And the girl hasn't said anything for odd reasons of her own?
This is... a bit different from the situation you describe at the beginning of this thread, Tinyblu. Also, if this is true, this girl isn't a "new toy" but an old toy, a girl he seems to have gone back to again and again, for years, ostensibly because she is "easy" when things get hard in his other relationships. If he's seeing her again, this is probably a bad sign.
You describe your relationship as "honest". Look at what I just wrote. Both of you are dating someone and keeping it a secret from the other. Does that seem like something you could reasonably describe as "honest"?