I think all of what you said is a good sign -- that she can be on good terms with ex boyfriends is as much a sign of maturity as her willingness to stop seeing him if it bothers you. So if you can get over your bad feelings, do so; if not, say so and take her offer to do this for you. I think it's okay for one partner to take heed of a partner's irrational emotions in this way now and again. But don't mistake it for anything more worrisome than just that, your irrational discomfort. You went to see Cats?