Pegging my bf went really really bad

Me and my boyfriend have been together almost a year and I really really wanted to try pegging him. I had pegged my ex's in the past. At first he said no, but then said he would be willing to take it slow, so I started with just fingering his ass and he seemed to like that. I did keep asking when he would be ready for pegging so he finally agreed to give it a try. I got a strap on and we started and about a minute into it he said "Stop! I don't like this!" Of course I stop and ask if he's okay. He had some tears that I thought were from pain and maybe I accidentally hurt him, but tears just started pouring down his face. I asked if he was okay and he just smiled and said he's fine with a cracked voice but tears were just streaming down his face. He let out a deep breath and said he was gonna get dressed and head home for the night. He assured me he was fine, but saying you're fine with tears just gushing down your face doesn't seem fine... He left about 20 minutes ago... I feel like I should try to talk to him or something. I have no idea what happened...

Edit: I didn't mean to pressure him... He liked the fingering pretty well so I thought he would feel the same about pegging.