Jess Mariano is Luke's troubled nephew that comes to live with him during season two of Gilmore Girls. He's played by Milo Ventimigilia and is definitely a love interest and part of a love triangle between Rory and Dean.
Lorelai tries to get Jess to understand that Luke is trying to help him
Jess: What are you sleeping with him or something?
Lorelai: Excuse me?
Jess: I don't know. The whole starry eyed 'you're so much better off, just give it a chance' speech. You're either really nave, or you're getting some.
Jess: Wanna play some poker? Five bucks a hand.
Jess: Ten? I can't go any higher than ten.
Jess: Okay, fifteen.
Luke: I don't want to play poker.
Jess: You sure?
Jess: Okie dokie.