Like spoil it a little but not a lot

This is up to date with raws… but it’s based off a novel. It will be revealed pretty soon that Josh is an omega. Chase overhears the talk about Josh waiting for Pete’s “mother,” sort of connects the dots and realises that Josh gave birth, but he doesn’t realise it was by him, thinks a diff alpha impregnated Josh. The problem is Chase actually has really low self esteem, so he doesn’t ask Josh about it or confront him for fear his assumption is true and Josh will leave him. Instead, his depression spirals and he nearly does smth silly because of his assumptions and love for Josh.
It’s only then that Josh actually realises Chase has this misunderstanding (Josh had been putting off telling Chase about Pete because it was hard to bring up/timing is weird/film schedule is busy/things were a bit up in the air after it was revealed that Josh was an omega etc etc). Josh still doesn’t tell Chase right away that he is Pete’s biological dad, but he does tell Chase that the omega he slept with a couple years ago was in fact him- not a dog, and he reassures Chase that he’s not actually waiting for another lover and sets up a meeting between Chase and Pete (to test the waters). After things go well between them/they bond, THEN he finally reveals the truth and series basically ends there. Which is very unfortunate, we never get to see them be a family unit, but through their cameos in the author’s other works, we do learn that they have two more kids (so three in total- 2 boys and 1 girl) and it’s implied that Chase is the more emotionally attuned, stay-at-home parent which I think is very sweet considering all Chase went through as a kid.

Somone told me because I made a guess saying that what if it wasn't a dog but it was actually Josh and they told me I was wrong

Are you talking about the part where Chase apparently did it with a dog? If so, Greyson lied to Chase because he believed he did it for his own good.