1) Fuck her while she sleeps,
2) Use GHB.
3) Apply both 1 and 2.
4) Didn't work? You fail hard.
Most likely your not good at it. And shes cheating on you.
"I don't believe in an afterlife, so I don't have to spend my whole life fearing hell, or fearing heaven even more. For whatever the tortures of hell, I think the boredom of heaven would be even worse." - Isaac Asimov
Hate to hurt ya ego, but obviously your not fucking her right. If shes horny and not wanting it then you got problems. Try some fucking foreplay damnit!!! Get smellin good, get the massage lotione (The shit that warms to the touch), tease the fuck outta her, AND GIVE THAT DICK TO HER RIGHT!!!! STOP THAT 5 MINUTE BULLSHIT!!! THERES A MILLION ANGLES TO FUCK HER IN!!! RAGE FUCK HER!! you be surprised how many girls rather be manhandled and willingly raped
I think you need to fix your premature ejaculation problem, then buy some chloroform