Here’s a couple of general tips that I’ve heard and found work to make me last longer…
Try a different position, like her on top. You can just lie there, and if she sits up, she gets good G-spot stimulation, whilst you get a break, and a nice view. It feels nice, but its not as intense as other postions, and it probably wont make you come as quickly. Just start off in missionary or whatever you like, and then when you’re getting close, suggest to her that you change. You can just say you want to try something different, if you don’t want to tell her you’re about to shoot.
Another “surprise technique” is where I’ll pull out when I’m getting close, and go down on her for a bit…I doubt any girl would complain. The caveat here is if you are using condoms, she may well taste like rubber / lubricant.
Doing these would of course be a bit more tricky if you lose your erection quickly…I think everyone has moments sometimes where you take it out to change position and it just goes.
Of course, if shes really enjoying it and on the edge of orgasm, I think you just have to stay in there and blow. She’d hate you if you stopped.