We can't blame the other person for getting emotionally involved with our spouses when they have an affair, we really can't.
Yes, we can.
We can -- and should -- blame them BOTH. "It takes two to tango."
Puppy
Fine we can blame both but the OM didn't know every detail, I'm sure she didn't explain everything to him. That would rarely happen when someone is in this situation.
Yes it takes two to tango, the only person I would be concerned with is the spouse in this situation.
And remember those feelings of lust/infatuation, those are chemicals generated in response to certain stimuli in a specific environment - we all went through very similar feelings when we began seeing our respective spouses, attraction is not a choice, love might be, but attraction isn't.