I dislike it. I think it comes from the UK. Also, as people marry less, the word becomes more common. I don't think it sounds lame for a 50 year old to have a boyfriend.
I think gay people used to say it before gay marriage, but now I think they should use boyfriend/girlfriend or husband/wife.
Spouse is a great term for use on forms so you don't have to write "next of kin" or "husband/wife". Most people don't refer to their wives as their spouse.