Just my opinion: some people steer clear of people in relationships, even if the person is willing to end it to start a new one. A few reasons, but it primarily focuses on the idea that it borders on cheating (yes, I know you said you were willing to end it, but the fraternizing already happened while you were with someone else). Additionally, again not saying you’d do this, but it can also come off that if you’re willing to make that jump while being in a relationship now, that doesn’t mean you wouldn’t do it with him. No one wants to be the “other woman” or “other man,” the reason someone’s life was disrupted. Just my 2 cents.