And again, not my point. The pact itself is fine, Mizora is fine. But the reasons for anything happening in his story are plainly wrong (I know, I sound harsh and uncompromising but they are!).
The whole Tiamat thing is a big complex interesting campaign in DnD. It is not a sudden event when a few cultists quickly assembled and summoned a goddess with no one noticing. The way it is presented here IS ridiculous, it is not how the summoning gods in DnD works. Makes the whole premise a cheap excuse for writing OR turns Wyll into an incredibly naive idiot who bought a clear ruse for a truth.
"Fall out with his father" is presented as "daddy issues of a little kid". From the moment Duke is mentioned Wyll constantly talks only about him, quotes him all the time, and cries about him. It is far beyond respect, it is needy and clingy. Good for a little boy, good for a teenager but not for a ground-up independent man, for a hero. It makes Wyll immature. It takes away from his heroic life. It makes him look weak. At this point, Wyll's father is a more attractive romantic option. At least he is an adult.
I don't think, his father issues are anything liek you describe, sorry. He hasn't seen his father for a while, did leave him on a bad note and now his father is in danger. Of all the things, that can be critizised, this is not one. You can have a heroic independant life and still be worried about your parents. Maybe the Tiamat thing was a ruse by Mizora - Wyll wouldn't know and Mizora wouldn't tell. I don't see a problem.
"We are all stories in the end. Just make it a good one."