The Rosie Effect is the sequel to superbly wonderful debut called The Rosie Project, but I suspect you can read it as a stand-alone. Although the protagonists are newly married, this is very much a love story, and a reminder to us all that there is no such thing as “lived happily ever after”: you have to work for it, compromise, fight for it. And if you fail, you should try and try and try again.
If you like Sheldon from The Big Bang Theory, you’ll fall in love with Don. You might even learn an obscure fact or two along the way. I’m betting once you’ve read the book, you’ll never confuse yellow and blue tuna again.