It's not that Paulie didn't like Tony,
Paulie's very transient. His mood - loyalty included - is dependent on his weekly income.
Paulie was upset with the way Tony was running things, but Paulie still listened to Tony and continued to obey every order given by Tony, that's loyalty,
Inaccurate. Watch season four again.
even if Paulie considered switching families the fact that he continued to obey Tony shows that Paulie is still very loyal.
But what factors decided his "return"? His defection across the Hudson fell flat. "Loyalty" doesn't really come into it with these guys. It's not an honourable, noble attribute; it's determined by capital gain.
