Lord, he absolutely misses his prince (who goes by Dandelion and is the lead of their band) and his band and feels a lot like "What's the point of me being here for this? I'm not the good one, I'm just some guy". Literally Dandelion (who is an exiled sidhe) hasn't made his band swear fealty to him, and may not have realized that they all view him as their prince regardless. Star managed to get ride or die for one kind of oblivious Good Man who made him feel better about his life choices and that guy ain't here.

He also was rejected from his clan because he got kind of tired of murder. Made the mistake of seeing humans as people just once, talked to a guy, and well, fuck me, right? He is not by nature solitary but he's been turned away from his herd and living as a solitary faerie since.

He will (try to or successfully) act disaffected as the lonely throws things at him for some time but they will still hit home, but he's that type; literally when taking a shortcut through hell he pretends he's not feeling the literal emotional assault of that landscape, but you know, he's actually pretty vulnerable.