First year the hardest...?

My husband and I have been married for a year now (but been together for around 10 years). We've had a rocky few months (he goes out partying most weekends and doesnt come back until the next day) and I feel that he's been distant. I recently upset him and he's said he wants to seperate but I still think we can work on our marriage, we get on really well, we've always had a great friendship but he says that marriage wise he doesn't think I'm on the same page as him. I really value the vowls that we made and don't think it's worth throwing it all away especially after such a short time(it doesn't help that a friend of his is saying he should leave). I'm just so confused on what I should do, since being married neither of us have been unfaithful but my husband thinks that I need to go out and see what's out there to really value him, I really don't see what I do so wrong......help please :(