I used to work at an Adult store and we actually had quite a few men come in with that issue. We had a couple of things that suggested...first off we had stimulant pills and drinks that can help with extra sensitivity and an increased sex drive. That did seem to work for most...some of those products were as follows:
Pill form:
Cockstar, Tibetian Balboa (most popular and expensive), Duro, Zencore and O max.
Liquid form:
Rush and jungle fever
There was also Kaboom which was like a Listerine breath strip that dissolves on the tongue

Some opted to try Extenze but that wasn't really for their specific issue so that normally didn't work.
Here's a website directly to the pills for more information if you're interested. http://loverspackage.com/c-239-aphrodisiacs-herbal.aspx

Secondly we would recommend telling your partner what you want, how you want it and always trying new possibilities, positions, tingling lubes/condoms things that create different stimulations.

By the end of the day 19 out of 20 customers had found something that worked for them and helped with their issue....

I do also recommend consulting a doctor if the problem continues or you have question about whether you should take any type of stimulant. I don't recommend the stimulants if you have any heart problems and especially not while drinking or under the influence of any drugs (aside from marijuana that doesn't matter) Not saying you do those things, just a warning that I would give anyone I was telling about these products.
I hope something in my answer helps and if not I'm sorry, but either way best of luck!