My same-sex partner and I, both US citizens, we’re legally married in Canada in 2011. The US government, of course, does not recognize our marriage. Will Spain recognize our marriage, since we legally were married in Canada? We are both retired and plan to move to Spain within the next 2 years.

If you have a legal marriage certificate then it should be recognized here. I’d imagine that you will need it verified with the Apostilla de la Haya or whatever it’s called though.