She was his trophy wife. He was 49 yo at that time and his mid-life crisis must of really gotten a boast.
She was the perfect profile of a woman who marries an abuser. Her family life as a child set her up for it.
She saw him as a "savior". She later saw herself as a "bird in a gilded cage"
One article given by a step-mother told about SP's father being an alcoholic verbal abuser.
I like the song by the Eagles "Tequila Sunrise", there is a line in there "every port of refuge has it's price" She had jewels, money, nice car, nice house...but look at the price she paid for it.
He totally controlled her and, in my opinion, everyone around her. Though, he appears to be a bully his self esteem issues made him feel less then worthy of her. Possibly also his guilt of killing Kathleen made him afraid of losing Staci.
JMHO..for what its worth