IMO I tend to be suspicious of some of the things she told Blake Ruff. He was the most important person to impress after she met him (seeing as all of her future security depended on being able to marry him.) She might have crafted a very plausible tale that didn't paint her in a bad light.
I realized that Blake's parents do what "old timers" do- they pick apart stories for the full truth. Face it, no one is perfect and we all tend to gloss over past failures and disappointments for lots of reasons. They were obviously concerned that FLEK might be with Blake for sinister reasons. There are plenty of mean statements about WHY a woman might be unmarried in her middle years of life. They probably expected she was quirky or "mental" but not prepared for the full truth here.
Another mundane theory I have is- FLEK might have bailed on a marriage, taking a lot of her husband's money with her. She might have been a typical "bad wife" who runs around, does drugs and is impossible to deal with....That simple fact would be enough to have an oil money family run her off. (God knows I put my brother's now-wife through the paces when she had not married yet- I let her know that if she was out to mess my brother over, she was going to be SORRY she tried...)
The truth might be the plainest truth- she did something a bit scummy that would ruin her potential as someone else's wife and didn't want anyone to know...