I'm sure I'm in the minority here, but there are many people who are happily married and have emotional affairs, like me, except in my case my affair isn't hidden. It's out in the open and my husband and boyfriend (both of whom I love dearly) are completely aware of each other and are even friends. We're polyamorous, which means having more than one love. We were married for 16 years before my husband brought up the idea of being with someone else. I was his first. I knew that he loved me and he agreed that if I had a relationship as well, he could handle it fine. And going on a year, we're doing great. I've discovered that I have a slightly kinky side that my husband isn't comfortable with, so he's fine with me doing that with my boyfriend. He's also had a girlfriend. The biggest issues for us are making sure we are completely transparent with each other, communicate effectively and make time for each other so no one feels neglected. If you're interested in learning more about polyamory and you think you're SO would be too, you can check out "Opening Up", "The Ethical Slut", and "More than Two" All excellent reads on open marriages and polyamory.
Keep in mind too, that love isn't finite. It only grows. I have three kids - when the 2nd and 3rd were born I didn't love the first one any less. The same can happen with men and women
