The Soulmate Theory by Sarah A. Bailey

Carter Edwards has always been a go-with-the-flow type of guy. Except when it comes to Penelope Mason: his childhood neighbor, and the only girl he’s ever fallen in love with. When he finally gathers the courage to make his life-long love for Penelope known, he finds that she’s already chosen a future for herself- one without him in it.
Penelope Mason is a planner by nature. She’d do just about anything to secure the future she imagined for herself, including leaving behind the boy she never planned on falling for. But at twenty-three, that future blows up in her face when she’s expelled by her prestigious university and forced to move back in with her parents.
Things only seem to get worse for Penelope when Carter re-enters her life unexpectedly. She forces herself to keep him at arms-length in attempt to stop him from learning the truth of her past five years. Yet, Penelope can’t ignore the realization that the one person who always made her feel most herself has walked back into her life at the time she needs him most.

Carter won’t give up so easily on his second chance with the girl of his dreams. But is Penelope’s past, and her looming secrets, too hard to overcome?