Remember, romance plots are not some magical black hole from which no other plot can escape. You can write both a thrilling sci-fi adventure and a romance simultaneously. As the writer, you are the one in control.
A common mistake with many romance plots is adding a lot of unnecessary drama or "will-they-won't-they plots". There's nothing wrong with adding a bit of tension, but many writers tend to take it overboard, bating the audience for endless chapters until one kiss in the final chapter. There's nothing wrong with saving the get together for the end, but the annoying part is that the readers never get to see the relationship, only the constant drama. If the drama is toxic enough, many readers may question whether the relationship is even worth getting together in the first place.
Giving the pair a healthy and mutually beneficial relationship is the best way to write any romance. Yelling and screaming, love triangles or toxic behavior can take away from the experience.
Another common mistake is getting so invested in the romance that you forget the rest of the plot. Don't bend the plot to fit the romance, let the romance happen naturally. Some writers take one look at their two characters and go "Aww, they're so cute together. They're destined for each other. It's perfect."
But much like real-world people, some characters do not always click. Ask yourself, if the world's under invasion from aliens or whatever, does there even need to be a romance subplot? Where does it fit in?
In a life or death situation, for example, how could anyone focus on romance? Are they so desperate for companionship in a wartorn environment that they would reach out to anyone for comfort, no matter who it was?
Your romance plot is not a tumor. It is a tree. Water it, give it sunlight, and water it daily. Don't feed it and it'll die, ruining your yard. Let it grow too much, and it'll become a weed that'll choke out the rest of the garden.