RB, honey, if I had the company of an attentive, attractive male friend I would be closer to throwing in the towel too. Watch out and be vigilant about your own temptations - satan wants nothing better than to destroy your marriage, you know that.
Granted, your W is playing a large part in it, and in your growing frustration. Just back up and try to gain some more perspective. I certainly cannot blame you at all. The way my marriage was before, if I had had the opportunity, I easily could have been the one having an A.
Just wanted to pop in with a splash of cold water on you to make sure you're doing the right things here. No judgment, I promise.
Forget the former things; do not dwell on the past. See, I am doing a new thing! Is 43:18-19
If it seems slow in coming, wait. It's on its way. It will come right on time. Hab 2:3