While I tend to agree with the diet and exercise advice, there are times that the dry feeling
inside the condom can distract the sexy mood and cause the loss of ***** flow down there no matter what sexual shape you're in. If the dryness caused by the condom gets to her as well, then it's a double whammy.
To remedy that, try a bit of lube
inside the tip end for yourself. Avoid getting it on your shaft or in the shaft part of the condom as you don't want it to slip off. After opening it, unroll it one turn, put a few drops of lube such as ky liquid or astroglide in the reservoir tip. Maybe a bit on your own tip as well

Leave a half inch or so excess condom off the end- roll it on, avoiding any lube going up the shaft. When on, stroke your head a bit to make sure it's a bit slippery and you have 1/2 inch of play with the excess. Make sure you put some lube on the outside for her as well.
The only problem you may have now, is coming too fast because it's going to feel like a BJ on your tip, while getting the vag treatment on your shaft.
If it's too intense you can scale down to one drop of lube, or I've even put saliva in the tip as it's less slippery than water/glycerine lubes.