I'm frustrated that my fiancé can't keep even the simplest things private.

My fiancé and I work at the same company, in different departments. I've recently started taking Illustrator courses and specifically asked my fiancé to keep it private. While it may not seem like a big deal to many, I feel more comfortable if no one knows from work.A few weeks later, he told me he had shared this information with a coworker. I was incredibly upset when I found out he shared something I explicitly asked him not to. What do you think?