Does romance belong in SFF?
What happens to a HoHo in a ruptured space-time continuum?
Really, those questions are all equally ridiculous. It doesn't matter what gender writes the story, or what gender reads the story. I will tell you what every halfway decent SFF and Romance writer knows:
Sex and romance must move the plot forward and further develop the characters to be of value to the story.
Sex purely for titillation? Nope. Never do it. Sex with or without consent has to serve the plot and characters involved. If you're going to write a rape scene, then you have to reflect how it affects the rapist and the victim throughout the story. You, as the author, cannot treat it lightly or make it a disposable moment. You, as the author, must acknowledge that in this day and age, you have a social contract with your readers to treat the before, during, and afters of the issue responsibly.
What about consensual sex? Same rules apply. If the captain and her lieutenant have a assignation, they still have to deal with all the morning-after issues. How does working together change? The rest of the crew will pick up on the differences in mannerisms or on the intangible tension. How does that affect individual relationships? Does it take a bright path? A dark path? Does it lessen the captain's influence over her crew? Does it make the lieutenant feel entitled to more authority than his title merits? Does it lead to mutiny because the captain indulged in something she'd forbidden her crew?
Detailed Tab A into Slot B Scenes, do SFF readers even want that? Some do. Some don't. It's up to you whether you want to write explicit sex scenes that can take two chapters to convey. If you want to write Fade to Black sex scenes, that's also fine. If you don't want to write sex scenes at all, then don't. That applies to every genre.
Whether you can write explicit scenes well...is a wholly different issue. There's a rather famous Grimdark author who is frequently teased by his readers for having the most awkward sex scenes in every one of his novels. He still writes them.
What about romance, does it have to lead to sex? Of course not. Some of the most emotionally fulfilling and reader-adored relationships are Slow-Burn Romances. The kind where the audience picks up on that first hesitant touch or witty-banter with subtext. Sometimes, the audience roots for couples that the author never intended to be viewed as couples. If you're writing emotionally compelling characters, then readers forming couplings in their imaginations should happen.
Oh, but what about the romances that are going to end badly for everyone in the blast radius? Or unrequited romances? As long as the set-up/decay of the relationship is well seeded, that's definitely going to show character development and at least one plot twist.
Does romance have to be in the book at all? Nope. Do not force a romance to exist if it doesn't suit the characters or the plot...or even the timeline. Three days is enough to get laid, but not enough for an accomplished assassin to complete her goal and entertain the distraction of a romance.
So, hopefully that answers "Does Sex & Romance Belong in SFF." Now, as for the whether the HoHo becomes a DingDong in an alternate reality...