I've read 60 novels and novellas this year ranging from kid's stuff (Roald Dahl) to wild sci-fi (Philip K Dick) to bloody horror (It). I just looked at my list and counted 36 that involved no sex or romance. The 80+ short stories featured even less. There are stories that need it and stories that don't. Inserting or removing an intimate relationship potentially changes every aspect of the story. Decide if it's organically warranted or improves the story, not whether it's needed. It's seldom needed. Unless of course you're writing a YA novel. I'm not sure you're allowed to write one of those without a love interest. Also, the "workaholic who discovers all she really needs to be happy is a boyfriend" thing has been done to death, and it's anti-feminist. If you do give her a romantic subplot, try not to turn it into a Sandra Bullock movie.