Of course there's no "correct" answer, but it begs an interesting question.
In terms of passing on genes etc. and surviving the human race, wife/girlfriend is the obvious answer.
But yes, ultimately it does depend on other factors. I've been with my girlfriend 7 years and my mother is in her 60's, and my partner is only 26, so it's not a short term relationship or a relatively young mother or older girlfriend.
Having said that I have a great relationship with both my parents but I'd hope my theoretical children would choose the same answer regarding me.
In terms of passing on genes etc. and surviving the human race, wife/girlfriend is the obvious answer.
But yes, ultimately it does depend on other factors. I've been with my girlfriend 7 years and my mother is in her 60's, and my partner is only 26, so it's not a short term relationship or a relatively young mother or older girlfriend.
Having said that I have a great relationship with both my parents but I'd hope my theoretical children would choose the same answer regarding me.