My best friend becomes a straight asshole when he gets a girlfriend?

I’ve known my best friend for over a decade he is genuinely an amazing friend he is always there for me when I need him and he is the sweetest guy however he turns into a straight grade a asshole every time he gets a partner, recently we just moved to a brand new place we discussed expectations and chores etc before we moved and everything seemed good mind you he didn’t have a girlfriend before this, he would always help me out with cleaning or dishes or whatever I needed when I was working (I’m a welder so I work long hours and I’m typically exhausted at the end of the day) we found a place that was way over our budget but he assured me when we moved he would gain employment to help me out with the bills and to split everything evenly well it’s been almost 3 months now and he got a new girlfriend. He spends all his time in his room talking to his girlfriend (they are long distance) he literally can’t even go to the bathroom for a second without being on the phone with her, he Dosent clean he constantly leaves a mess for me to clean up I buy everything for the apartment with no help (groceries, toilet paper, cleaning supplies etc) I also pay majority of rent which for me is 1350 and he only pays 750. I work my ass off just to make ends meet while he sits on his ass on government assistance talking to his girlfriend 24/7. The last straw I had with him is when I bought 2 medium pizzas for myself to last me a few days until I can go to the food bank when I woke up I went to grab pizza and 3 slices were already missing from the pizza I know damn well I didn’t eat then I found a McDonald’s bag in the garbage so he had food, I wouldn’t be bothered by this as much if he was actually trying like enrolled in school or something I wouldn’t mind paying more for a little while until he landed a Job right but he’s not even trying he’s just taking advantage of me at this point.
My best friend becomes a straight asshole when he gets a girlfriend?
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