Unless you have some issues with your spouse, there is no room for an extra marital affair. I mean if both partners are happy how come a third person comes in the picture. If you are doing it with the knowledge of the spouse means he/she is doing the same thing with your knowledge and both are cool with it. There is no pint in living together then.

I don’t think it will be true love, it is just infatuation or fling. But if their marriage is weak then their is possibility of falling in love with someone else.