Bel means someone who beats you or otherwise abuses you.
"Partner" seems to be the word most used in my circle of friends, many of whom are gay or lesbian. Some of my hetero-and-legally-married friends use it, too. I've also heard "companero" with the Spanish pronunciation for a male partner, although I have not heard an equivalent for a female partner.
When my husband and I were in the pre-nuptial stage, but living together, one of my friends called us "hubby" and "wif", abbreviated from the legal terms because, she said, we weren't fully "husband" and "wife" yet. Cute, but grating.
I sometimes called David my "um", because people who didn't know us well would sometimes introduce us to others as "Elizabeth Creith and David Syme, her - um - "; this confusion was caused because I didn't make David take my name when we married.
Re: boyfriend/girlfriend being adolescent, I have heard ninety-year-old women refer to their boyfriends, said "boys" being of about the same vintage. Ditto for adult males referring to a woman of forty or more as a "girlfriend".
