Well, it's not supposed to be romantic. It's kind of meant to be subversive - with the woman taking control of the situation. He lied to her - and married her with the intent of never having kids, but didn't tell her that at all. (If he had - she'd never have married him. It would have been a bad match for her.) Instead he made her believe she wasn't getting pregnant because it was her fault and he fully intended to have kids. (In short he was manipulating her to get what he wanted.) Keep in mind the time period? This is Regency - where if you don't have children, the woman is left with nothing. She inherits through the kids. So if anything were to happen to him - his cousin or a distant relative would inherit or someone three or four times removed, leaving her penniless. When she found out - she continued to have sex, but she kept him from pulling out. It didn't hurt him - it's not rape. If anything it is less painful for him to come inside than outside.
And less messy. And she's carrying the child - to protect her financial interests.

Basically he was being an ass.

It's important not to project modern sensibilities onto it - because in today's world, in most cultures, that wouldn't have been a problem. (Although it is unfortunately in others - we live in a patriarchial society, where women are still treated like property in many places in the world.)

Bridgerton isn't really a romance show a la Hallmark, it's social commentary kind of similar to Jane Austen. Shonda Rhimes and her show-runners are commenting on gender politics and inequalities along with racial and class inequalities through a satirical romantic series. I've not read the books, so I can't say whether they did it too or not.