So, before this continues, let me clarify about the uncle. He is her mother's half uncle who recently met her (he never know his half-sister existed). He's my wife's same age, and we recently moved near him. My wife has had an extremely intimate relationship with him for about 8 months, texting, skyping, and she hid it from me at first. When I found out, I assumed she was having an affair with him. I do not believe that do be the case, but I can tell my wife is obsessed with him, will do anything for him, tells him everything, and he replaced me in her life as her emotional support and friend. I believe (though my wife denies it) that he has a massive part to play in her falling out of love with me.
They are not having a physical affair, but she is almost acting like she is having an emotional affair, or at the very least a unhealthy relationship with him.