Honeymoon phase over or?

So lately I’ve been feeling a bit confused.

My partner and I have been together for 11 months and we don’t text as much, do much of what we use to and he just doesn’t seem to care anymore... I miss the way we were,also mind you this is my first relationship and we are both in our 20’s he’s been cheated on in the past. Is this his way of protecting himself? Honeymoon phase over or has he lost interest in me.

P.s I’ve tried talking about it but it ends in an argument..