Have you tried using a condom? Maybe with less sensitivity you can last longer.
First off, you aren't a failure. Shame on them for not being understanding of your differences. there are plenty of guys who have this reaction as well. I'm sure there is a more professional explanation to it.
But as for my opinions/suggestions: Have you tried self exploration and have tried to figure out what the differences are when it is just yourself and how you feel when you are with a partner?
Perhaps some self evaluation and exploration would help you to better understand. It may be that you are just more sensitive than most others. Have you attempted to experiment with multiple ejaculations in a single session to see if there is a difference in length b/w each one? I think you should explore just how much of this is physical and mental.
Hope that helps some. And don't be discouraged, you just need a kind woman who is understanding and more willing to help find a balance b/w her sexual needs and yours.