Yikes! That is a hard one. To be honest, I think I would try to avoid having feelings/dating them if I knew they had it. However, if my partner did and had contracted it BEFORE we got together, it'd be hard to leave him over it. I just think it would be so terribly sad and depressing to have to go through the troubles of it especially when one partner doesn't have it because you have to take such cautions and I'd constantly be scared that I'd contracted it.