The Worst Kept Secret (Secrets #2) by Q. B. Tyler

I've had a crush on the single dad next door, ever since I was thirteen years old.
Theo Graham is charming. Sweet. Absolutely gorgeous.
But, I'm not a little girl anymore.
I shouldn't want him.
I can't have him.
I should know better than to want my best friend's dad.
My best friend, Theo's son, who may or may not have had feelings for me on and off for the past eight years.
Wanting my best friend's dad was the one secret that was never supposed to come out.
Except now, he wants me too.