So what actually happened?

It seemed like that's what happened, yes. I don't think they had any kids, though.

They left that for the viewer to decide. It appears they grew old and built a like for themselves. Maybe they had some kids. It really doesn't show.

I think they probably killed themselves. Maybe they went for space walk together and untethered.

They both would not have died of old age at same time, so one of them should have got in medical pod to see the Homestead place. If they didn't do that, then they must have killed themselves.