lover; sweetheart; boyfriend; girlfriend
Refers to a romantic partner, regardless of gender. Can be used for both casual and serious relationships.
He took a walk in the park with his girlfriend.
恋人募集中です。
I'm looking for a romantic partner.
I got a new girlfriend/boyfriend last month.
He found himself a girlfriend at university.
She broke up with her boyfriend last week.
The two of them have been dating as boyfriend and girlfriend for three years.