Used when someone shows excessive affection or romantic interest in a noticeable way. At the party, Mark was all over her, trying to woo her with compliments.
Pro Tip 2/3
Not Always Welcome
May imply that the attention given is too much or not reciprocated. She seemed uncomfortable when he was all over her at the cafe.
Pro Tip 3/3
Public Display
Often involves physical affection seen by others, like hugging or kissing. They were all over each other regardless of the crowded room.