That really.
How do people go from being someone that you thought you knew inside out for several decades, that you thought loved you, cared for you and could trust 100% into someone you just don't recognise.
Prepared to lie not just to your spouse but your parents, children, close friends. Severing ties with those previously very close when they give advise you don't like. Cutting people off that you were previously very close to.
Prepared to use even a sick elderly relative as an alibi.
And being someone although not perfect but was always kind and compassionate into someone so cold and calculating.
Not taking any responsibility for what they are doing, everyone else is wrong. It's everyone else's fault 'I made him cheat' and 'I drove him to it'.
Is that just how a cheater becomes, is that normal?
Do they really not care, are they happy to lose so much just to be with someone they don't really even know?
Are they the previous mostly nice person with the affair partner? Because if they were like they are with everyone else they wouldn't even be interested in them surely?
Can they not see the damage their actions are doing to all those in their wake? Or do they just block it out.