In my case this EA my W was involved in evolved into a full fledged PA. This was caused by a large degree by my inability to see the signs and if I did ignored them and continued my ways of driving a wedge in our M.
The EA starts harmlessly, in my W case a longtime friend and schoolmate from HS. I recall vividly 8 years ago my comments to my BIL at a family dinner that I felt the OM had intentions on my W. All was dismissed as me being paranoid, but as we all know, WE know our genders and tactics too well. This EA grew steadily for years until when he found out about our M problems, he offered her a night at a remote resort "to talk and get her head clear". This is where he proclaimed his longstanding love for her and kissed her. The rest went downhill very quickly.
So I agree with BB on the points of EA, I also state that they need to be discussed with you spouse. The effort it takes to upkeep a M or R is not spent in the right direction when it is going to another individual.
As to what you would do OAW, my mistake was pursuing it and finally discovering and witnessing my greatest fears. That in itself has caused me personal grief and issues that have taken many months to get over and learn to control it. It is only now I can really focus on my changing and efforts for our M.
Sooooo, I would caution you to try and discover what is going on. The truth, in my case, was worse than the speculation. What the key here is, changing yourself to become that which is attractive and desirable to your W again. This of course is my humble opinion.
F4W
Through honest giving of my love I will recieve 10 fold in return.
Just because a person does not love you in the way you want, does not mean they do not love you!