Sure. My stubborn position is still, you can't help who you fall in love with, but as you notice "holy cow, I'm falling in love with someone," apply the brakes stat and figure out the existing relationship. If the figuring out includes terminating that relationship, then zoom away with the person you've fallen in love with into the sunset.
Sorry you went through that, Blatham. I went through something much less dramatic, but have also seen lots of similar situations. I never like "oughts", but have said so often here, usually directed at men, that I really personally dislike justifications for affairs. One mutually monogamous relationship ends, another begins -- no prob. One mutually monogamous relationship is still going while another starts -- not so much. Had a few run-ins with CodeBorg about it. His comments have indicated that he feels there is a double standard -- men can't do it, women can -- and I was thinking of him as I saw this and at first didn't want to comment, since I like the people involved. My own opinions, once stated, can of course be completely ignored.

I wouldn't really expect or want anything otherwise -- just a little for-the-record observation.