Some of his friends could be skeptical about whether it's really Harry. After all, coming back from the dead is a very rare and almost unheard - of thing in the wizarding world. This could lead to a period of testing and proving his identity, which would strain their relationships at first. But once they are convinced, they would have to deal with the new Harry who has been through the experience of death.
Harry's return could also bring up old unresolved issues among his friends. Maybe there were things that were left unsaid or arguments that were never fully resolved before his 'death'. Now that he's back, these issues might resurface and they would have to work through them while also dealing with the fact that he's alive again.
His friends might be overjoyed at first. But then, they could also feel a bit of unease. For example, Hermione might be worried about the implications of his return and how it fits into the laws of magic they know. Ron, on the other hand, might be more focused on just having his friend back and want to jump right back into their old adventures.