Nope. I developed feelings for someone else while in a relationship, but I told my girlfriend straight up, and we split up for a little bit. I told the other chick too, but she was seeing someone, (which I knew, but I just had to get it off my chest) and we just became better friends over it and my ex and I got back together until the relationship just flat out died.
... and then I ended up hooking up with the other woman five years later, anyway.