Boyfriend has issues ejaculating..

So this seems really really odd but my boyfriend seems to be having trouble with cumming..

He was a virgin (we're 17 so it isnt like hes lied about that) and I was his first. He told me its because hes always found it tricky to get hard, the first few times we was making out he started getting hard and now its pretty easy for him, however, when he does get hard he either

- reaches climax and doesnt actually cum

- cums but doesnt realise and just goes soft (doesnt feel it coming or climax)

- is normal and feels it and lets me know

it sounds really weird so here it is in more detail.. its not that he just doesnt want to pull out as its happened when I have given handjobs and hes cummed and didnt even notice like usually guys tense up or moan but he just cummed and started going soft and then got really embarresed that he didnt know.. another time i was sucking him off and he started saying hes gonna cum and moaned and tensed up and had a dry orgasm but acted as if he had cummed this has happened a few times with sex as well as bjs and hjs, however sometimes he says hes gonna cum and he does..? its a bit scary as we had sex and he suddenly went soft when it was in me and pulled out only to see his cum dripping out as he hadnt realised he had cummed and didnt feel it coming and it was really lucky im on the pill. I've said he needs to go to the doctors but hes really embaressed.. does anyone have any ideas.. thanks..