He kept kissing her in her neck. His heart started to pump a lot harder to make sure that he wasn't losing the amount of blood that was going to make him shift as a safety. When he lost 25% of his blood and he was human, then he would change to wolf. But if he was wolf and then lost 25%, then he turned back to human. Slowly he pulled her shirt up a bit, not wanting to startle her by doing that.