I definitely don't think that your W is having or immediately planning an affair based on the evidence you have presented. However, some things about your situation aren't computing with me so I have a couple questions. I apologize if you already covered these points and I missed it.

1) Is your wife infertile?

2) What is your financial situation relative to your wife? Who makes or has more money? Has this changed recently?

3) When you turned your wife down for sex in the past (assuming that she did attempt to initiate fairly often) what reason or reasons did you typically give for not wanting to be sexual?

"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver