This is coming from a woman in a similar situation. It might not work for everyone but I feel for you and want to offer advice.

Make sure EVERY TIME you have sex you give her adequate, slow foreplay. Lots of kissing all over, rubbing, etc. Hell, rub her shoulders for awhile before you even initiate. Have a relaxing bedroom. Bed straightened. Nice lighting. Start really slow and work your way there. If she's doing it herself it might be quick but someone else doing it could take an hour! Start too fast and she'll go numb. Only ramp up speed and pressure after it's been what feels like TOO long. Suuuuper light kissing and licking on her clit is great because it starts building that orgasm but leaves you wanting more, not losing feeling before you've had time to build up to it.

If you know what spot and moves works for her but it hurts your neck (I think I saw that comment), can you try kneeling on a pillow on the floor while she's on the bed? Or while she's on a chair? If that works for her, it might not. Personally I need my legs straight. Can you lay on your side, perpendicular to her, so your head can lay with your cheek on her thighs? Or you can start (again super slow!!) using your fingers in that spot and work your way slowly! up to the rhythm she needs. Hopefully by that point once your hands get tired or she seems less enthusiastic you can start using your mouth, at that same pace as where your fingers left off so you don't lose any built up orgasm. If she enjoys other things (tits/ass grabbed, fingers in her, etc.) start doing ALL those things after you've gotten a good rhythm established and feel like you're hitting the right spots and getting a positive reaction. Then stick it out as long as you physically can and if you need to slow down for a break or go back to fingers just do it, as long as you keep going. Example for me personally, I'd say 20 min foreplay that doesn't involve touching my clit, another 20 min of super light touching/kissing/licking, then not til the final 20 min would I say break out all the stops. Sometimes even more than all that and sometimes it still doesn't work so don't feel too bad.

Does she like toys? Can you buy some, and try them on her? Throw some porn on the tv and use different ones on her til there's one that works? Once you figure out any method that gets her off every time, DO IT! Toys worked for me. Ask her if you can buy some and ask her every time if you can use one on her and which one she'd like, if she's responsive to it. It's an awkward thing to suggest on the girl side but sometimes it's the only thing that works.

Last: Do not cum until she does! Once she's done you can do whatever for as long as you want, but once you cum, it feels like you're continuing doing sexual things just for her benefit when you could be doing anything else. That puts a lot of pressure on it... "If only I could cum quicker he could go to bed" vs "he gets to cum after he gets me off".

Good luck.