Perhaps you should change your attitude about it.
Men and women are different, though I'm sure you're already aware of that. But as such, in cases like this it's sometimes merely a matter of finesse.
Bear with me while I explain.
I want you to think about what your relationship was like back in the time when you were "do(ing) it 3 an 4 times a day."
Now, think about what's changed since then.
Have you more responsibilities? More stress? Less time?
Do you grab her as though she were a steak and you were a starving dog?
Women like to be LOVED. They often want to be caressed and held; talked to; romanced. If she feels as though you love her and though the act of sex is not your top goal, she's a lot more likely to want to give you what you want.
In other words, sex is the culmination of the expression of your love for her, not a prize you win from the shooting gallery at the carnival.
Change your behavior and watch her change hers.
P.S. It might also help if you think of it as "making love," not "getting sex." There IS a difference.
