"I bet there could be some interesting sociological research at some point on what happens post partner death in heterosexual vs. homosexual couples in long marriages/relationships." — YES! Definitely, that would be fascinating and valuable research. It's very plausible that platonic-social dynamics might be different in hetero vs. non-hetero populations, and this could indeed make a difference in quality of life. Quantitative research often doesn't have enough data on people who self-identify as LGBTQIA+ in order to be able to draw conclusions with true statistical significance regarding those identities, unfortunately. But we absolutely need more representation in datasets, so hopefully it begins to happen. Thank you for saying this!