I'd like to add a thought here.
I had some similar experience with a girl i dated who was sexy and we shared an insane chemistry that we could feel in the air between us like magnectic fields.

we would spend a lot of time kissing and teasing and playing with each other.
and when it came time to get down to business, sometimes I would be completely
soft.

the problem was, no one can stay hard forever. and time flies when you're having fun. looking back on it we'd been spending 3-4 hours messing around.

after we figured that out, we handled the time better. and it was good.

anyway, maybe that applies to you, and maybe not. but it's something to consider.