Can’t ejaculate during intercourse

So I’ve a bit of a problem, yesterday I had a girl giving me a amazing blowjob and was also riding between her boobs but I couldn’t ejaculate. At some point she said I want you to cum so use your hands, when I did that I managed to ejaculate. The girl was cool and didn’t say much about it but I felt bad since she was trying really hard.

The strange things is that I have sometimes the opposite and cum almost within 1 minute…

From what I found here it seems I’m probably desensitised but also something I noticed is that my foreskin seems to shift behind the head and the head gets totally swollen and painful.

Has anyone experienced something similar?

Thanks!