What Joe did didn't seem all that bad
Maybe I'm in the minority here - probably am - but to me what Joe did by activating Mia's adult mode and then screwing her was no more an act of betrayal than it is when a married woman enjoys a vibrator. That kind of thing happens all the time and is not viewed as infidelity. He didn't know he was screwing a sentient being.
I can understand why the family would be disgusted, but his behavior was portrayed as infidelity, and I simply don't think that's realistic.