I think Ianto's madly in love with him. I think possibly one of the reasons that that bothers me is that it's been implied, both on and off screen, that this is Ianto's first same-sex relationship. A lot of his slightly ambiguous behaviour therefore comes across to us, the viewer, as uncertainty as to how to behave, what to do and where the boundaries lie. With Jack's experience and history, I think we expect more from him in the way of guidance, assurance and, above all, clarity, and we're not being shown that, which makes it look very much like Jack is happy to throw Ianto to the wolves and let him figure it all out on his own. Poor Ianto. :(