Many of us here on WS have wondered about the relationship between Kelsey and PF. Just my 2 cents.....
Maybe Kelsey's life prior to meeting PF was busy in school getting degree, church activities and she wasn't a party scene type of girl. She has been described as shy in a few articles I've read and maybe a little naïve. If so, I can totally see her using an internet dating website.
Cowboy Pat (thanks MassGuy) while not suave and so charming IRL, probably could come off quite pleasantly online. I believe he did sell her a 'bill of goods' as another poster pointed out. My ranch, farmer, dog breeder blah blah blah,
Kelsey seems like an honest, forthright person so she could have easily been duped and did little investigating his claims.
He convinces her to move and 'let's get married and live happily ever after'. She believes this, she falls for him. Moves and once she's able to see him consistently IRL, she starts having concerns. She gets pregnant and decides to push those aside for baby K's sake. She loves her new job and coworkers, so buys her own place perhaps thinking this will nudge CP along.
Things worsen over time, and at some point Kelsey gives Cowboy Pat an ultimatum and well, Cowboy Pat doesn't take kindly to those. Anger, custody, financial motives, could be any and all of them. JMHO