Venom had a plan to win Anne back. Eddie vetoed that plan, because it mostly consisted of eating off Dan’s head, which Eddie did not approve of for a number of reasons. The most obvious one was that Dan was a good person who did not deserve to become a snack for the monstrous alien living in Eddie’s body. The one most relevant when considering Venom’s mostly non-existent morality was that Anne would probably not be very happy with them if they bit off her boyfriend’s head. And the final reason, the one that Eddie really hated to admit, was that he kind of really liked Dan.