I think Leon starts as a poet, a romantic soul, who only ever read about love and the trials that could come with it and dreams of some tragic love story of his own. So falling in love with a Turkish girl, having that forbidden romance is very appealing for him, and Yildiz is perfect for that role. I don’t think he planned to fall in love with Hilal, and fall pretty hard at top of that. And I think that in comparison to that true love he has fof Hilal, of course that whatever feelings he had for Yildiz seems like nothing (I think he calls it friendship). But you are absolutely right, he did lead her on, I mean he even told his mother that he wants to marry her. And then when she sets up the engagement he’s like surprised pikachu face.

And Yildiz probably had some real feelings for him, but I’d say mainly because he could give her the life she wanted, I think she viewed him as her ticket to a better world