A woman who enjoys having someone come on her chest doesn't have to surrender her feminist card for letting someone come on her chest. But you don't enjoy it—it makes you feel objectified in the wrong way. (Most of us, feminists included, enjoy being appreciated for our parts and our smarts.) Use your words: "I don't like it when you come on my chest. So that's over." He'll have to respect that limit or he'll have to go. If he doesn't feel comfortable coming inside you, IUD or no IUD, you'll have to respect his choice. He can pull out and come somewhere else—in his own hand, on his own belly, or in a condom.