Responses
Oh shit...this is probably gonna be the time skip... But I don't really like that. She dumped her kids off on him then thinks she can just come back, take them, and head off again? Its just not cool at all, to her kids or the other people involved. I'd be really upset if I were in Yuuji's position. Its not okay to tug people left and right without taking their feelings into consideration, especially considering how much he did for her.
My theory is that Yato will go with his mother. The reason would be to get taller than Yuji, because I think Yato takes this as a goal before he can be with him. Maybe Yato will come back being 18 or something to not leave Yuji any more excuses.