My boyfriend peed in my mouth during blowjob

I’m just gonna start by saying this was 100% unintentional, and I literally had to comfort him cuz he was almost crying because he felt so bad and was so embarrassed. So when I first gave him a bj he stopped me and told be he felt like he was gonna pee. I told him to relax and that’s it’s probably cum because I thought it was impossible for a guy to pee with an erection. So he relaxed and he came and everything was fine. So a few more times it happens, and he’s always hesitant because he still thinks he’s gonna pee but nothing ever happens. Anyway last night I was over and he warns me that he’s gonna cum soon and I start feeling it in my mouth. It tasted a little weird and then I realized there was wayyyy to much and I was like holy shit he’s peeing in my mouth. obv I move my mouth immediately and it continues to spray and I’m just in shock and it’s dripping from my mouth and in my hair and on my clothes and stuff. So I’m just sitting there with an open mouth, piss dripping out and I’m like “get me a towel”. Anyway we cleaned up and he was soooo upset. He thought I was gonna break up with him, and I just told him it’s not a big deal and it’s fine. Honestly it really wasn’t that bad and I just tried to laugh it off because it really isn’t that big of a deal. My only concern is how this is possible and what may be going on. How can we fix this so it never happens again? He cums normally when he masturbates but he always has issues with feeling like he’s gonna pee when I go down on him. Is it something I’m doing? Help!

Edit: yes he peed beforehand