You liked Bruno (you both are close friends), but Bruno has a girlfriend, while Abbacchio likes you.

The Passione decided to throw a party tonight, and you're going to the party. You thought that Bruno's girlfriend wouldn't come over to the party, since she wasn't part of the Passione. You stepped in the party, you look around and find Mista, Giorno, Narancia, Fugo and Abbacchio chatting with eachother, you take one more good look and find Bruno giving a drink to his girlfriend. You get surprised, but don't show it. You look away and walk over to the chatting group and notice Abbacchio looking at you with a rare, soft expression, though you don't mention. Abbacchio looked back at the boys when he notices you looked his way, Midori didn't know that he liked her.

As soon as you enter the chat, everyone looked at you

Giorno: "You finally showed up, what were you doing to get late?"

Giorno asked curiously, as the other are also curious and Abbacchio is too embarrassed to look at you after that eye contact.