That's a good explanation. Not everyone is going to understand the nuances of every word, not everyone understands their impact on others or the baggage their own language/ culture/ worldview carries (good and bad)

But here's the biggest tip: if you're a white person and a POC tells you something is racist, then it is. They decide, not you. White people don't get to moderate, what-about or gauge how badly racist something is or even if it is. Nope, not our lane. OP says something is racist, BF's correct response should be to support her. Not protect the SIL.

And probably do some soul-searching to make sure he isn't (assuming he cares) and figure out why that particular thing is racist if it isn't obvious to him. People can grow