Yes I was with my fiancée and I could not get a erection I do not understand why I could not please help I do not know if I was nervous or what?

Hi Sgjmark,
If you are in otherwise known good health, it likely was simple anxiety. Depending a great degree on age, possible medical reasons can range from diabetes to high blood pressure to an enlarged prostate.
If the problem continues, definitely see your doctor, just to make sure there aren't any underlying conditions. Though if you are in otherwise good health, I wouldn't worry too much.
One other factor could be if you consumed any alcohol prior to your intimate session. This can relax a person, but larger amounts can make it difficult to develop or maintain an erection.
Some anti-depressant medications can as well effect one's sex drive.
Hope this is of some help. Take care. :)

I am 29 years old I hope it was just being nervous I am healthy thank you for the info.

You're welcome. :)