Up till recently her desire in sex has always been a certain way, but as she is getting older she is changing and feeling differently. Im trying not to be crude or offensive so bear with me. Due to a medical condition I now have to sometimes take a pill to make love with my wife , Now being as she had her affair back when I was pretty much in prime shape and didnt need such medication ( which doesnt always work) my fear is another affair because of I not being able to satisfy her needs/desires which have now changed and gone way up......I never thought at 34 almost 35 this could happen to me but now faced with this, im scared out of my gourd that one day it will happen again another affair...Irregardless of how well we are right now and never feeling closer and in love...
any comments would be appreciatted.

Ummm....not trying to step over a line or be to graphic, crude, or offensive either-sorry if it comes across that way-but there are lots of other ways to satisfy her needs if the pill doesn't work.
There's a thread on EN that might help you. Maybe these other methods are something you or she is unwilling to try but there is more than one way to get the job done. I have a dear friend whose husband is completely incapacitated in that way but that isn't an issue because he's figured out other ways to accomplish the task. I would think about trying other methods and then when you can-great -when you can't there are other ways.