Just one of the details I realized later

She had a different motive when it came to learning languages.

At the beginning of the relationship, she was learning my native language. Whenever I spoke in my own language, she would say, "It makes me happy when you speak your native language." Looking back, I think that was a good example of mirroring.

A few months later, she started learning another language. What happened next? She ended up dating someone who speaks that language.

I guess it wasn't really about the language itself. She was simply attracted to the idea of being with someone who spoke it.

You already know the rest of the story.