It isnt' an issue of him wanting to be with someone else
He is married and is addicted to an affair.
You need to decide if you are willing to help him end that and explore reconcilliation or if you will not accept that and want divorce.
It is humanly possible to be emotionally committed to a woman in the long term and to have a short term affair with another woman. This does NOT dismiss his long term commitment to you, even on an emotional level.
Often people having affiars will say soemthing like
"I love you but I am not in love with you"
But this is them confusing the feeling of romantic excitement with the commitment of marriage and family that brings its own wondeful feelings - that are MUCH MUCH HEALTHIER and LAST much LONGER
Your husband likely needs a FT to help him understand the difference. Infidelity makes it almost impossible to distinguish during the affair itself.
He's confused his impulses and adrenaline for emotional love and commitment... he has the former with HER, and the latter with YOU... this is NOT a matter of him just wanting to BE WITH her.
I can pretty much assure you he doens't KNOW what it MEANS to be with her. Affair couples long term success rate is less than 1%. Once they run off together and are under the same roof they learn eventually that love isn't the same thing as excitement...
Don't confuse these two the way he is... its not healthy for you or him.
