<human>: My fiance is very upset that his Mom(52) has met someone after the death of his Dad(56)/her husband. It has been two years since he abruptly died of a heart attack. His Dad wasn't the kind of guy that was loving and dotting and gentle. He expressed his love through providing financially to the family and was kind of emotionally unavailable to his wife but they still loved each other greatly. My fiance is the only biological son out of four sisters and two adopted brothers.

 Recently a male friend of hers has become more and more involved their family's lives and he's been helping with my fiance's two adopted brothers. They are both preteens and one has autism and the other has schizophrenia. This guy's presence has upset my fiance and a few days ago he found out that his Mom has a sexual relationship with the guy. This kind of pushed my fiance over the edge and he hasn't spoken to her and has been very moody to me. He feels that she is moving on too fast and she must not have loved his Dad as much as he loved her. I spoke with his Mom and she is still sad about losing her husband of thirty years and misses him but at the same time she said it's nice to have someone emotionally be there for you and take care of you in that sense. She doesn't love this guy and they are FWB but she isn't closed minded to what may happen in the future. He isn't a bad guy, he has actually helped out quite a bit. It's just my fiance is very angry about the relationship.

Can you condense the text into three sentences or less?
<bot>: Fiance's Mom is moving on after Dad's death 2 years ago. Fiance isn't happy at all.