Negroni:

I Really Love Angsty, Bitter, Broken-Then-Reunited Romance Stories

The male and female leads break up at the beginning, then suddenly reunite. He was blindsided by the breakup back then, so he's both in love with her and angry at her. He acts cold and pretends they barely know each other, but secretly gets jealous all the time. He wants her to comfort him, but she doesn't pay him any attention. He falls apart and completely loses it, then goes all out trying to win her back. Male lead romance.