I recently re-read Sugar Daddy by Lisa Kleypas. I think this is a really good book and not very predictable like a lot of other romance novels. Here is the summary from the inside cover:
She's from the wrong side of the tracks
Liberty Jones has dreams and determination that will take her far away from Welcome, Texas - if she can keep her wild heart from ruling her mind. Hardy Cates sees Liberty as completely off-limits. His own ambitions are bigger than Welcome, and Liberty Jones is a complication he doesn't need. But something magical and potent draws them to each other, in a dangerous attraction that is stronger than both of them.
He's the one man she can't have
When Hardy leaves town to pursue his plans, Liberty finds herself alone with a young sister to raise. Soon Liberty finds herself under the spell of a billionaire tycoon - a Sugar Daddy, one might say. But the relationship goes deeper than people think, and Liberty begins to discover secrets about her own family's past.
Will they find their hearts' desires of will heartbreak tear them apart?
Two men. One woman. A choice that can make her or break her. A woman you'll root for every step of the way. A love story you'll never forget.