But would a pet affect this? Isn’t endangered status about wild animals?

In colloquial language, “chemicals” is fine IMO. It’s clear from context that it’s not H2O. Just like substance abuse is only about drugs, not cornography.

Long and difficult question. For me, “The art of loving” by Erich Fromm was where I truly learnt this stuff. Inspired by Marx and Freud. The main point is that love starts with you, the subject, and how different kinds of love are connected. Could be what you’re after.

NOTE: There is some sexist and homophobic stuff in there. I will not defend it, but the spirit of the book does not rely on these points, in my opinion.