Hi SDD.
My marriage to STBX began with an 'affair'. I put the word in quotes because many people on the board disagree as to whether it was an affair, as the person I betrayed was not my husband, but my boyfriend. I think that what matters is how I felt about what I'd done later, and the effect it had on my marriage.
My marriage to the man I cheated with lasted for 11 years, then he left me for another woman (we have now been married 12 years, but the last anniversary wasn't anything to celebrate, as he was living with OW <img src="/ubbt/images/graemlins/frown.gif" alt="" /> ). So, as Suzet* says, he did it with me, and now he's done it to me! I understand that my marriage actually lasted much longer than most affair marriages - I think that 5 years is usually quoted as the limit. Those that last longer than that are likely to be the ones that 'make it', I think. Unlucky for me!
Here's what I think undermined my marriage, because of the way we got together (i.e. by cheating):
* I felt horribly guilty about what I'd done to my BF - still do, in fact. He did absolutely nothing to deserve the horrible way I treated him. Believe me, he really suffered. I had 'forgiveness' dreams for years, in which exBF and I would meet up again, and he'd forgive me (actually I haven't ever seen him again - I'm never going to feel that forgiveness, even though I'm sure he moved on years ago and forgot/forgave me in time).
* The guilt built a wall between me and my H. I couldn't tell him about how I felt - how I often actually regretted leaving my exBF for him, and thought frequently about leaving and returning to exBF! After the 'passion' wore off - and it quickly did - I never felt that my H filled my needs quite as well as exBF had. We had lots in common, yes, but the 'ease' I had felt with exBF was never there with H.
* I never fully trusted my H. I don't think this OW that he left me for was the first - just the only one he fell 'in love' with. I remember, quite soon after we were married, I found a condom in his wallet. I was on the pill at the time. I asked him about it, and he said it had been there for a long time, since before I was on the pill and he'd kept it just in case and had forgotten about it. I only half believed him, but I let it go. Of course he was lying!
* However, we had children together. If we hadn't had children, I have no doubt whatsoever that the marriage would have failed much earlier. You see, I knew for a long time, even before STBX left me, that I loved him much more than he loved me. But he adores his children. He was happy enough to stay before, but when he fell 'in love' with the OW, he didn't think twice about leaving, I think.
It took me a long time to realise that what I had was actually an affair marriage. I think I'd been posting here as the BS for several months when it really dawned on me! See, even more than decade on I was still in the 'fog'! <img src="/ubbt/images/graemlins/rolleyes.gif" alt="" />
Of course, STBX says that the OW is the 'love of his life', she is his 'soulmate'. I don't believe in 'soulmates' any more - I thought STBX was mine, and now he's living with someone else! It may be that they marry (he has said they intend to marry after the divorce) and it lasts the rest of their lives.
The odds are stacked very heavily against it, though.
Alph.