Here is my feedback on the funk.
Take an interest in her interest. Ask her what she has come across lately, maybe even plan a small road trip to view some "interesting" cemeteries nearby as an aid or encouragement to her research. Do a little planning in secret on your own, maybe even including some favorite take-out food that she likes on the way there or back. Getting in the car is a chance to get out and maybe open up the scope of conversation. Maybe try to understand her motives: maybe she sees a collapsing society around her and is looking for an anchor, some stability in the world. Maybe she is forming a view of how she wants to be known in the future, who knows? Try to get a talk going and be quick to listen and slow to speak-see where she is coming from.
I'm just saying maybe shift the scenario a bit. "Hey, let's hit the rack" isn't the best method or motivator as years go by.