Absolutely! It’s incredibly easy to talk to children as young as five or six about boys having boyfriends. There isn’t anything sexual about it.
I once wrote a story about my Evangelical Christian friend. His 6-year-old asked me why I kept coming around to the house with my new boyfriend.
Of course, he didn’t know the guy was my boyfriend. My friend interrupted to tell his son the very simple truth. “That’s Jim’s boyfriend, and boys can have boyfriends too.”
The little boy accepted that with simple ease. No discussion of sex was necessary, no inappropriate adult themes raised.
That’s how easy it can be.