Does this sound like a bi-polar disorder or just someone that wants out of a relationship?

My fiance and I are in the process of buying a house together. Closing is next Wed, December 17th. Both of us have homes and we are renting them out. I asked him if he could put a fence up for my tenants and because they have three dogs. He said it’s their problem and they should put up the fence becaause it’s their dogs. I already told them I would and they have a two year lease. I don’t want to go back on my word. He said he would put it up and then we went to Home Depot and all he did was complain and whine about it and he said that I should tell them we’ll put it up at a later date. I got angry as he had a month to tell me this and NOW he doesn’t want to?? I could have found someone else to do it or I could have done it myself! I need it up by Sunday! Ok- well, in Home Depot he was acting really odd and grumpy. I saw something I liked to fence off the deck and grabbed it. He got really mad saying -’oh yea you know what to do so YOU do it’. Basically, I never installed a fence and he has so NO I don’t know what to do, but I know what I grabbed was good for the deck. Anytime I asked him what we need for the main fence he got sarcastic and angry and I was sick of it so I said ‘I’ll just put up the fence.’ because to me it just seemed like he didn’t want to and it’s my house – so I might as well do it. He then got sarcastic again saying ‘Oh, I gotta see this. How are YOU going to lift the heavy wood..’ In fact, one time he put a moldy piece of HEAVY wood in the cart. I said I didn’t want it because it was moldy and there was non-moldy wood. He said ‘you go ahead and get it then’. It was heavy, but I managed to do it as he gave me a really evil eye look – almost scarey look- that I did it. Well, I got fed up and just figured I’ll do it all my self and proceeded on without him and asked the sales guys for help on building a fence. He then said he was leaving and that the deal with the house is off and that he’s going to the bar next door to find a ride home. I said ‘All this because of a fence’ and replied ‘ No, it’s not the fence. It’s you and your communication skills.’ and took off. Well, of course I kept my cool and I was upset. I continued shopping and didn’t know whether to go find him or let him be. I went home. He called but I missed it. I called him back. He said he was walking home in the pouring rain. I drove out to find him. When I did he was already 3/4 of the way home and soaking wet. I pulled up to him and asked him to get in the car three times. Each time he mumbled something like ‘F U..’. couldn’t really hear him. I finally said ‘ Fine, walk in the rain if you want’ and left. He came home, dried his jacket in the dryer, took a shower, packed a bag then Drove off into the night. Just a few days before he was talking about having kids and helping my Dad in retirement by having him move in with us and HE even asked my Dad to move in with us when we get the new house. He said he loves me and all this and that – and Now – it’s FU, I’m leaving you.
Sorry for long description, but I didn’t want to leave details out in case the problem really is ME. Is it me or is there something wrong with him? Is he bi-polar or just want out?
Just a few days before all this HE asked my Dad to move in with us in our new house and he wants kids with me, etc…