I started it last night Jordy I'm 4 episodes in already! I love it! here's my theories so far :
Spoiler:
I think either
A - The world with his son is real because I think the world with his wife is too happy and everything works out better in that world, plus his wife seems to be handling losing Rex almost too well
Or
B - Maybe neither world is real and he's actually in a coma or something? and what he actually has to do is wake up from both worlds
I dont know if 1 reality is real and 1 isnt yet but if thats the case I really want it to be Hannah's. I know its horrid since you should always go with the kid but Rex is a bit annoying and Hannah is lovely plus a few things happen which youll get to.