noun
being seriously in love with an idol or celebrity; fan who is genuinely in love with an idol or celebrity
Slang used in idol and fan culture. Refers to a fan who has romantic feelings for the idol, not just admiration. Can describe the feeling or the person.
See also: ガチ
彼はアイドルにガチ恋していて、毎日SNSをチェックしている。
He is seriously in love with the idol and checks her social media every day.
ガチ恋勢のファンは、握手会で緊張してうまく話せ
Fans who are genuinely in love sometimes get so nervous at handshake events that they can't speak well.