Unexpectedly Mine by Kyra Fox

She never expected to fall for the dirty-talking mechanic... Eric "Mac" Mackenzie leads a lackluster life. When he meets Zoe, a young genius with an impressive academic career, he can't stay away even though he knows she's way out of his league. Despite it seeming like they're worlds apart, their unexpected connection sparks a whirlwind romance neither saw coming. But as their feelings deepen, Mac's insecurities about his own worthiness begin to gnaw at him, pushing him to distance himself from Zoe. After all, what does a down-on-his-luck mechanic who barely finished high school have to offer a brilliant and beautiful woman with a bright future? Unexpectedly Mine was previously published under the title Pass Me By as part of the BFF Series. While the basic storyline has been preserved, the story has undergone extensive rewrites and includes new scenes that weren’t included in the original publication.