Chase and Abby came from different worlds, or rather, from different sides of the race track. He is a blue-blood with familial and societal responsibilities that don't include falling for a mere trainer--not to mention the fact that he is already spoken for.
Abby, on the other hand, has previously had the non-privilege of dealing with the rich and snooty, and has no desire to get mixed up in that world again.
While Abby is loath to admit it, sparks are flying between the two---sparks that Chase realizes don't exist in his current relationship.
With Dymond Enterprises in jeopardy, a girlfriend who won't give him up, and a horse who doesn't realize he's a champion, it's going to be tough for Chase to convince Abby to give him a chance. But he's not giving up until he proves to her that diamonds really are a girl's best friend.