In general American society, “boyfriend” is clearly understood as one’s unmarried male adult romantic partner, still perfectly applicable to an adult man of any age.

“Girlfriend” can be understood as one’s female adult romantic partner or one’s platonic adult woman friend.

If you don’t like it, here are some other options:

1. Beau
2. Companion
3. Partner
4. Suitor
5. Sweetheart
6. Admirer
7. Confidant
8. Intimate
9. Lover
10. My man

If you don’t like those options, maybe you can agree between each other on a cute little nickname.