Take a Chance on Me by Beth Moran

Emma Donavan is the eldest of five daughters, and the only one not married or engaged. She makes cakes for everyone else's happily ever afters and has almost given up hope on having her own. But when her neuroscientist sister Bridget comes up with a project to match a couple by their DNA and a compatibility test, have them marry and agree to be filmed for 9 months for science, Emma decides to give it a try. But when Emma is paired with her sister's best friend Patrick, life becomes even more complicated.
Patrick has been secretly in love with Bridget for years but now that she's getting married, Patrick decides to join her compatibility project. He fudges the results in order to be paired with Emma. But will being married to the wrong sister help him forget Bridget or did he just make the biggest mistake of his life?
This one was just too unbelievable. First thing, I got lost with the introduction of too many characters, spouses, and children and it was a bit overwhelming. And while I understand the frustration and heartbreak of an unrequited love, why would you pair yourself with their sibling, being forced into constant connection within their close family group? And Emma, knowing that Patrick still has a crush on her sister, goes ahead with the marriage anyway! I just don't get it. I'm sorry but this one just gets a meh! from me.