Super-short summary: portrait artist Alexa falls into an affair with mega-mogul Guy after she's hired to paint him; several months later, he breaks it off because he's getting married to apparently save his banking empire. She falls apart pining for him and he eventually tries to come up with a way for them to be together, but still feels like he must continue with his arranged marriage. There really is no major conflict about why Guy can't be with Alexa if he wanted to, or at least it isn't explained, so the title really is a misnomer. Nothing about her is forbidden.
I keep going back and forth about whether I liked this or not. It's weird not to know. This eventually rang all the typical emotional bells of unrequited love, but it was a shallow story that could have been a lot more. Guy and Alexa's affair was never even shown beyond the "he walked out of the bedroom," descriptions (seriously!), so I had no clue why these two had any grand passion. Told from Alexa's perspective, Guy would contact her when he was in town and wanted sex and she would be there, then he would leave, and she loved him even though he barely acknowledged her. Uh, why? She had a family that never appeared, a best friend that vanished halfway through, a job that she loved that appeared only when it had to do with Guy and the plot, and there really just was nothing else to the story other than Alexa pining for him, hating him and pining for him again. Intersperse that with the really uncomfortable workings in Guy's head as he moans and groans about how miserable he is with absolutely no thought to Alexa. His poor bride-to-be barely even made it onto his radar.
There's very little reason given here to like Guy; he's utterly selfish and morally ambiguous (so is Alexa, at one point). Apparently his actions are excusable because he's super-rich and used to getting what he wants and later on, he turns some of that around and explains the affair with Alexa (because she was so "forbidden") as a sanctuary because she never treated him like a super-rich man. He's still really not attractive as a hero, even as his faults are explained away with unbelievable little fluff plot devices. Alexa is maddeningly inconsistent; for a heroine who is supposed to be so cool and composed, she goes off the rails nearly immediately. Still, if you can get past not knowing why on earth she loves this cretin, then her emotional story at least is interesting.
If this had been given a longer format, this may have been a good story. If I could have actually figured out why on earth these two loved each other and had there been a little more character development, then maybe I would have understood why they acted the way they did. They may have gotten their happily ever after (that can't be a spoiler, that's what these books are all about), but the way they got there was awfully strange.