に惚れる

fall for

→ に
phrase Rare #26,530
fall for Used when developing romantic feelings or becoming infatuated with someone. The person one falls for is marked with に. 惚れる is somewhat colloquial and can sound stronger than simply liking someone.
JA: その子に惚れるのか?
EN: Are you going to fall for that girl?

トムメアリーに惚れることになろうとは思ってもみなかった

I never imagined that Tom would fall for Mary.

トムは自分がメアリーに惚れるとは思ってもいなかった

Tom never imagined he would fall for Mary.

望みのない誰かに惚れるなんてばかばかしい

It's ridiculous to fall for someone you have no chance with.

トムメアリーに惚れることになるとは思っていなかった

I never thought Tom would fall for Mary.

トムは自分がメアリーに惚れることになるとは思っていなかった

Tom never thought he'd fall for Mary.