“Help. My wife won’t perform oral sex.”
If she has a bad gag reflex she should focus on the tip, which is the most sensitive part of the penis. Instead of trying to put your entire penis in her mouth she can give you a hand job while licking and sucking on the tip. A helpful hand can also give more momentum, and even help some men orgasm sooner. Anyone who has ever surfaced, gasping for air, asking “are you almost there”? can appreciate a quicker finish.
She might also try humming. First it feels good, and second it’s hard to gag when you’re humming. Also, relaxation is key for her. It might just soften that reflex.
If she does not like the taste of performing oral sex, I encourage you to get Masque: Sexual Flavors strips. They mask the taste of semen and other sexual flavors with fun flavors of their own (mango, strawberry, chocolate, and watermelon).
If you address her issues with fellatio, I think she will be more willing to get down with it. Show her that you are taking her concerns seriously and remember the best way to receive something you want is to give a little first.