Ianto's eye-roll indicates that he's not really impressed with Jack's answer. He's going to let it go, for now. Once he's back he's sure he'll find out. It's inevitable. Ianto's good at finding things out, and he's good at being patient.

He's probably the most patient man alive. He can wait a week to return to work.

"Alright Jack. I can see you can't wait for my arse to leave. So I will." It occurs to him he has no where to stay. He supposes he can hole at in a homeless shelter until he has an alternative.

He didn't exactly expect a welcome-home snog, but he didn't expect to be pushed out the door either. He wonders if Jack really doesn't want him around, or if the immortal is performing another one of his stupid martyrdom attempts.