Spanish question?

I dont know if it's just my high school spanish but I'm reading "Landslide" by Kathryn Nolan and there's the following passage:

“Having fears?” I’d pressed back, too aware of the giant diamond on my left hand. I actually hated diamonds, but we’d never talked about what I wanted. “Everyone has fears, mijo. It’s marriage. It’s a… it’s a lifelong commitment. There’s nothing wrong with having fears about that.”

But she's talking to her fiance? And calling him...mijo (my son)?

Am I misunderstanding?