Musannaf Ibn Abi Shayba 1:499

Jarir narrated to us, from Mughira, from Hammad, who said: If a man kisses his wife while she does not desire that, then ablution is incumbent upon him, and there is no ablution upon her. If she kisses him, then ablution is incumbent upon her, and it is not incumbent upon him. If he experiences desire, ablution is incumbent upon him. If he kisses her while she does not desire that, and she experiences desire, ablution is incumbent upon her.