I didn't like it. Their connection was ok, but wasn't all strong in my opinion.
I don't see them ending up together if she hadn't been pregnant. FMC would have married the Prince she was told to marry, while MMC wouldn't have known who she was. He had the ability to figure out who she was for 7 months and never did. I do think he was celibate for those 7 months though based on little comments about not being able to look at anyone else since being with her.
FMC was so confusing, she was going to marry basically a stranger to protect her sister (so her sister wouldn't have to be the heir), but she refused to marry the father of her children for some reason. It didn't make sense to me what the issue was and why she was refusing so adamantly to marry MMC. How was she not afraid that her father would marry her off to someone else or that him being King he could just take custody of the children? She was described as so selfless, but she didn't quite come across like that to me.
MMC was so cold most of the time that I didn't really care for him all that much.
It didn't really feel like they were in love with each other when they told each other that they were. It just felt like book needed to end and they needed to be in love. P.