Women being gay: they were dear friends who lived together for the past 50 years, owned several cats together, never consorted with men, and are now being laid to rest under the same tombstone as it was their eternal wish never to part. What close roommates they were!
I didn't think Spinster was a derogatory term, it was literally a job title of something that women could do to achieve financial independence back in the days when men owned their wives.
I don’t think it started as a derogatory term, but it became so. People would use it to imply that someone was ugly or otherwise defective, so no husband would want them. A man unattached is still seen as more acceptable than a woman unattached even today.
In the same way that any word for an independent woman can be derogatory. It wasn't used in a negative way when I was growing up (in a deeply old-fashioned part if the UK), and as a kid before I knew that being a lesbian was possible I thought of it as aspirational