If you are worried about causing a scene, butt in about something else. Hey <NAME>, I heard somebody say you like <TECHNOLOGY>! I'm a huge fan too! If he's re

If you are worried about causing a scene, butt in about something else. Hey <NAME>, I heard somebody say you like <TECHNOLOGY>! I'm a huge fan too! If he's resistant to your interruption, be more forceful in trying to engage him. Maybe sit down next to him. Worst-case he becomes aggressive towards you, but so long as you stay bright & friendly, everyone else will see him picking the fight. That way you can try to defuse the situation indirectly. Maybe you get him engaged in conversation, or maybe the girl seizes the moment to excuse herself. Maybe you offer to the girl, Some other girls were looking for their friend, they said she had a blue shirt, was that you? If he seems reasonable yet misguided (rather than a total asshole who knows the girl wants nothing to do with him), you can optionally try leading him away and quietly saying something like, I noticed that girl was starting to feel uncomfortable, tone it down/back off/try a different tactic. Anyway, that's what I'd do if I was trying to avoid making a scene.