A popular romance trope is the "secret baby" or the "unexpected pregnancy" following a one night stand. I depsise that trope because anyone living in a literate society should know by the age of puberty how babies are made. It's not "unexpected," it's irresponsible.
Where the romance trope and real life diverge is the consequence of that unplanned pregnancy or "secret" baby. In romance, the ending is happy: mother, baby, and father get a happily ever after. (Substitute stepmother or stepfather where appropriate per story.) Anyone who's raised children know there is no true happily ever after.
Again, here's where reality clashes with expectations. Children have minds of their own. Yes, they really do. What they don't have is the cognitive maturity and life experience necessarily to make wise choices or decisions about their own lives or the lives of others.
Wisdom has little to do with intelligence. Smart people do, say, and believe stupid things all the time. Intelligence also has nothing to do with morality. Some of the world's worst criminals and more morally degenerate people were and are brilliant. That's one thing comic books tend to get right: the most dangerous criminals are the smart ones.
In another forum, I recently came across a distinction between "realism" and "verisimilitude." It struck a chord with me, as I have often urged writers to inject realistic elements into their stories. After all, what anyone can verify within a minute's Google search should be verified. Elite military operatives don't hold hands when exploring an unknown cavern. Horses don't eat mushrooms. Nobody with a lick of sense bales and stacks hay shirtless. Regardless of the kind of bullet, something has to propel it down the rifle's barrel. If not gunpowder, then what?
Realistic elmenents give even the most wildly impossible stories verisimilitude, a semblance of truth, that sense that, yeah, it could happen. As I've said before: if the reader can't trust you with the small, easily verified details, he or she won't trust you to lead him or her into the realms of impossibility.
When initially drafting a story, verisimilitude isn't the author's first goal. The greater concern is getting the story down in tangible format. The first round of review and revision leading to the second draft tackles the large plot holes, the areas that don't make sense, the jumps back and forth in plot. A second round of review and revision leads to the third draft. That round focuses on checking facts—making sure what's supposed to be realistic really is realistic—and massaging language. A third round of review and revision results in a fourth draft. In that round, the author focuses on copy errors. At that point, the manuscript may finally ready for beta readers or an editor.
Take responsibility for your stories to ensure verisimilitude and teach your readers to trust you.