The First Rule by Nicole S. Goodin

Darcy.
Being left at the altar wasn’t part of my plan.
Neither was my ex-fiancé’s twin brother offering to be my sperm donor.
I could have said no. I should have said no. But that’s the thing with hindsight… once you’ve got it; it’s too late to take anything back.
Ryan.
The situation was complicated, but the rules were simple.
Rule number one: No catching feelings.
Rule number two: We do this one time and one time only.
Rule number three: This is our little secret.
We made a hasty agreement fuelled by heartbreak and liquor, but it turned out to be so much more.
Darcy Shearer isn’t the same woman I laid eyes on five years ago – everything has changed since that night… except the way I feel about her.
I gave her my word, but now I’m taking her heart. She forgot the most important rule… that they’re all made to be broken.