If we are both in the office, and I start using my phone to send you text messages that are harassment, and/or messages to our coworkers that make fun of you, is that the companies problem?

If we are now both working from home, does that qualitatively change the situation? When working from home, what even is "outside of work"?

Hmmm, that's interesting. How much of a person's personal life (both good and bad) is the responsibility of the employer? And why.

Eh, some companies ( financial institutions, brokerages and so on ) may have regulatory requirements that puts onus on those organizations[1]. That is mostly the argument for keeping personal and work life separate, but that ship has sailed a long time ago.