I had the same problem with my wife (girlfriend at the time).

I took forever to come. At first she liked it but then, well you know the story... Anyway here's what worked for me:

When you're alone, try making yourself come faster and re-train yourself. My personal record is 2min.

Also, just relax and don't focus on the big O, focus on making her feel good, get in tune with her rhythm and soon you'll be coming right along with her...

Don't worry, sometimes it just takes time for people to get used to how they make each other feel. Emotions like trust and insecurity get in the way just as much for men as it does women, believe it or not.

Hope this helps...