My memory of sitcoms and comics from the '50s agrees with you.

That's all that I have to go on; I wasn't alive myself back then.

All the same, I still think that ‘lover’ is a contemporary word. A bit old-fashioned, and usually singular, but I was alive for a time when a gay man could introduce another man as his ‘lover’ and it would be perfectly natural, with no other word that would mean quite what he wanted to say. (Now he could say ‘fiancé’ or even ‘husband’ and that would seem natural, but once upon a time it wouldn't have.)

ETA: Also Nornagest's ‘former lover’.