You sure are one lucky guy, your girl must be something in bed, but to be asked to do it again when all you want is to sleep… must be very irritating and disappointing.
It must be doubly hard for the girl, may be even depressing. Well Viagra is not for you as you don’t have any problem with normal erection. You can go for some natural herb based medicine. There are some wonderful Indian and Chinese herbs like Shilajeet etc. which can have you perform like your girl always wants you to. But you must be wary of the cheats as there are many of them when it comes to sexual stimulants.
I suggest you to go for
Stiffnights which a special blend of Herbs, Mushrooms and Greens and extract from rare Chinese plants. If you are wary you can go for free sample.