[Oh, so that's what happened. Shiro had been a little defensive before, because he's protective of his kids and all, but hearing that makes him feel a bit bad for Ronald.]

Look, I'll give you some advice, since it looks like you really need it: don't treat this like a continuation of what happened before. You'll just scare him away if you do. If Yukio doesn't remember it, start over. If you guys were 'mates' before, then you should know how to befriend him.