He can’t cum??

Me and my boyfriend have been together officially for 3 months(today actually),a little over a month ago I gave him head,he said it felt really good but he couldn’t cum due to it being cold as we were outside.On Saturday he went down on me for the first time he then asked me if I wanted to have sex,I said yes but he told me he wasn’t able to get up,he continued on me and then I gave him head.This time we were inside,he was hard,moaning and seemed to be enjoying it but he still couldn’t cum.He reassured me that it wasn’t me and that having sex would probably help but he had to go home as it was late,I’m confused to what could be wrong.I want to make him happy in a physical way but I’m not sure what to do.We are very comfortable around eachother but he does have anxiety if this could make any difference.Have you guys ever experienced this?Have any ideas why is happening?Or what I can do to make him cum?