Originally Posted by
vertical_sky
I can understand her jaw getting tired... what she might want to try is switching between her hands and her mouth. When her mouth gets tired, she should use her hands for a while, and even while using her mouth, keep her hands around as added stimulation. She should also experiment with different pressures... go from squeezing really tight to just a feather touch, with her tongue, with her hands, and placing sensation on different parts. Switching off between her hands and her mouth, and also her mouth and her vagina (switch when one part gets too tired/sensitive) will result in less taxation on her body.
You might also want to look into exploring kinks. Does your wife have any fantasies? Do you? How often do you discuss them/act upon them? You said you are extra patient going down on her... How often do you try mutual masturbation/oral?
Long story short is, I believe if sex drives are not too divergent, partners can work through it if both are willing to try new things.