This is a really difficult book for me to grade. The problem is that there's a great romance in here, but there's also some issues that would have had me pitching the book across the room if the rest of the writing weren't so good.
What really worked for me were the scenes of poignancy interspersed throughout the novel. Gabby's coming to terms with her feelings for her ex, Tyler. Jon's struggle to overcome a legacy of abuse, and forgive himself and his brother. Gabby's strength in fighting for a relationship that is fulfilling and and honest is commendable.
What didn't work for me is some of the retrofuck gender attitudes that seem to be populating category romance these days (I mean seriously, are we swinging back to the 80s?). Gabby's mother is considered weird by both Tyler and Jon because "she hasn't had a boyfriend in 30 years." Tyler calls it "scary." Jon hasn't had a girlfriend in a long time either, no one's calling him scary. Maybe her mom's gay, or maybe she just doesn't need to have a partner to be happy. I mean, why is this presented as WEIRD? Is it not the 21st century?
There's also a bit that made my teeth grind - where Jon assumes because Gabby doesn't like him, and because she's boyish looking, that she's a "man-hating lesbian." I'm pretty sure the author intended this section as humorous, but it really made me dislike Jon as a character, and made it very difficult for me to see him as a man deserving of a romantic ending. I know men who make assumptions like this because a woman doesn't fall all over them - and they're assholes, straight up.
The abuse sub-plot also gave me some concerns about the long-term happiness for Gabby and Jon. Near the very end, Jon loses his cool and beats the shit out of a man who's verbally abusing his son. I get the reaction, but dude - not healthy. The fact that everyone encourages him and tells him it was a good thing to do - ehhhh. I guess I'm just a little wary for Gabby settling down with a man who hasn't conquered his addiction to alcohol yet, and who has violent outbursts.
I do, at the very least, appreciate a read where an abused child DOES get to have a happy ending (heaven knows, in Literary Fiction Jon would've probably died in a gutter somewhere after drinking himself stupid).
So, at the end, I would give One Good Reason a qualified recommendation. I'm hoping some of the blatant sexism disappears from category romances soon though, or I'm going to have to quit reading them.