<human>: So my boyfriend of 2 years (we had been close friends for 3 years before we started dating) and I just moved in together. It's been about 2 months of living together and he has become extremely pessimistic and just not fun to be around. I'm a pretty optimistic person so coming home is beginning to become an absolute downer. 

We've had a few fights since moving in together, which I expected -- nothing too crazy. But during the last month, he barely smiles and everything he says to me is a put-down. I can't figure out if it's work-related (he has a stressful job) or if it's me. I've brought up his negativity before and he just tells me to stop taking things so personally. He's a no-nonsense person, very analytical and grounded and I knew that about him before we lived together. But everything feels exacerbated now that we live together. I feel like I'm walking on eggshells around him because he's upset all of the time and won't tell me why. It's just draining being around him. I try to do nice things for him all the time, like do his laundry, cook him dinner, etc. It works for a bit and then he's back to a bad mood and gets upset when I ask him why he's in a bad mood. 
  
Has anyone dealt with their partner being negative all the time, and how did you handle it?

Can you succinctly summarize the text in 1-3 sentences?
<bot>: My boyfriend has been in an eternal bad mood since we moved in together, and I'm hoping someone who has been in a similar situation can offer some advice.