Legend Im not really sure. I mean if it was a sex chat line, probably not. If I was certain they never had any intention of meeting them and was just using it as a bit of a turn on, I could probably forgive. I have had a couple of long term relationships and if I thought for one minute my other half had never thought about having sex with someone else, I would be a fool. Its not a lot different to thinking about it, if you dont actually do anything.
And yes, I agree that there are married men out there looking for affairs as there are married women, i think the internet makes this a lot easier but in my mind that isn't the basis of a solid relationship. Best to be found out and dumped, they would do it anyway. I think the internet gives opportunity to people who might normally struggle to find a date, sexual partner etc because although the immediate attraction might not be there you can connect on a different level.