stealing someone's romantic partner
Refers to the act of intentionally taking another person's boyfriend, girlfriend, spouse, or love interest for oneself. Often used in discussions of relationships, dating, and social drama.
She stole her friend's boyfriend through romantic partner theft.
Stealing someone's partner is an act that hurts those around you.
不倫 refers to adultery or an extramarital affair, which may or may not involve stealing a partner from a committed relationship. 略奪愛 specifically implies taking someone away from their existing partner.
Compound of 略奪 (plunder, pillage) and 愛 (love). The term likely emerged in modern Japanese to describe the act of 'plundering' someone's romantic partner.