Some people tend to disconnect after their initial attack. Such people are difficult to throw, but since they aren't actually attacking, who cares?
Without getting my hands on both of you, I wouldn't necessarily agree that *his* intent is missing. It could be yours. Or it could be both. Neither of you is really senior enough to assume that what you're doing is "right." More likely, the flaws in your ukemi directly align with the flaws in his technique.
I'm just going by what my sensei says. Even he has a tough time with me sometimes. I don't know WHY I do it, I just do. All I know is that it makes this student frustrated. Thanks for the comment!