![Wink ;)](./images/smilies/icon_e_wink.gif)
![Smile :)](./images/smilies/icon_e_smile.gif)
Like others already suggested, tie her up to your bed, if I remember you did this one-time before, then start performing cunnilingus on her. Your tongue, your fingers, a combination of both, I guess you know want I mean, whatever "gets her motor going". Bring her to the brink of an orgasm, but don't let her cum, back off and let her cool down a little but not much and start again and when she's again at the brink stop again. Repeat this a few times before you finally let her cum.
Of course, I can only speak of my own experience with my beloved wife, someone else will maybe react differently, but this drives my better half absolutely crazy with lust, always.
Oh, she will get frustrated during that process, probabely she will start cursing you, but it will also fuel her lust and desire immensely. Yeah, she will be mad at you (in good way
![Wink ;)](./images/smilies/icon_e_wink.gif)
Maybe, this could also be a way to coax some of her hidden desires out of her. You could tell she must tell you one of her fantasies before you let her cum.
However, this is only a little suggestion from, but I'm curious what you might think about it.
Oh, before I forget, I agree with the previous commentator a cock ring could do wonders for your hardness. Not everyone is comfortable with that, but at least you should try.