No appropriate term

The Love of My Life. Life Partner. Soulmate. Significant Other. -- I have one of those. We have a very strong commitment to one another and will probably augment that commitment with a legal marriage one day (assuming the marriage tax repeal becomes permanent). In the mean time, I have a hard time coming up with a term that is appropriate in professional conversations. While I view our commitment as just as binding as a legal contract, I can't actually use wife/husband and be telling the truth. Boyfriend and girlfriend makes me feel and sound childish. All the others make me feel as if I'm hiding my sexual orientation. I just want a term that is the truth and that doesn't immediately cause someone to look at me and think, "ah, yes, I thought you were young".