I think most experts agree that most affairs run their course, and end within 6 months to a couple of years. However, that statistic includes one night stands and affairs where there isn't much emotional investment at all, but more of an affair of convenience (for at least one of those involved). Affairs where both are emotionally invested have a higher likelihood of becoming more. That's not to say that those don't blow apart too- they do- just that a deep emotional affair is harder to break. I know couples who eventually married their affair partners and have been married for years.
It is for this reason, in part, that I advise you to take action more quickly. I know that you don't want to right now, and that's ok, I just wanted to define further where I'm coming from.
Absolutely, a "deepening emotional bond" would be one of the primary downsides of allowing an affair to continue, un-battled. There are others, too:
1. Squandering of family finances. In my case (and remember, my wife's affair only lasted 3 months) I put the final price tag well over $40,000, from legal fees (hers and mine), gifts/clothing/plastic surgery (things she did to make herself more attractive to OM), to the 2-year lease on a 2nd residence that we ended up having to secure in order to live separated.
2. The cheating spouse's medical health. Studies show that affair partners engage in unprotected sex at far higher rates than the population at large, and the risk of STDs (or worse) is very real. The sad, horrible stories have been told on this very forum.
3. Continued exposure of the children to the marital dysfunction (fights, arguments, cheating parent staying out 'til all hours and not being available to them when they need/want them, etc., etc.).
4. Emotional health of the betrayed spouse erodes with each passing week of an unrepentant affair. Lost weight, depression, illness, etc. Basically, it's emotional abuse, and when you consider that it's coming at you from someone who supposedly loves you, and swore to forsake all others for, it can eat at you to the point where it's very unhealthy for you. For men, it can be downright emasculating.
5. It exposes the cheating spouse to what is often an emotionally unhealthy relationship (disregard this if you feel your wife's OM is emotionally/mentally/spiritually/financially GOOD for her).
I could go on, but those are my main ones that I encourage betrayed spouse's to consider. Don't get me wrong, you can't control nor neatly STOP your spouse from deciding to continue to cheat on you. But you CAN base your decision-making from a place that considers the above threats to the family in their calculus.
