I think more than anything, Julian just feels genuinely bad about these girls. Only partly because of their "relationship" with him. But mostly because of the kind of stuff they're subjected to while he himself just sort of became their "boyfriend" and then when it was done, he was done.
He's well aware of how much "easier" he has it compared to them. I mean, both Sofia and Madison are NOWHERE ANYWHERE NEAR the career level that he's in right now. And he still talks to Zara mostly because he's worried about her after the stuff he hears.
He keeps trying to tell her that maybe it's safer for her to go make a career back in Europe. It's just...she's gotten into some bad situations in the US.
Sorry I have to stop claiming your characters. It's just my language I promise lmfao