Me and my half sister

So about a year and half ago me and my sister were exchanging messages and somehow things kind of turned into us telling each other how we were attracted to one another. Eventually nudes were exchanged. There have been a few attempts to meet up and actually hook up. She has a boyfriend and she’s very committed to him. She’s told me how she feels about me and how turned on she is by the idea of us actually fucking, but how she doesn’t want to cheat on him, but also but how bad she wants me to fuck her. We only live about an hour and a half away and in the past, we’ve tried to meet up so we can fuck, but for one reason or another plans have fell through. I’m just wondering if I should give up on the idea so that I don’t ruin her relationship, or should I just be patient until she is actually ready?