When is it okay to harm or kill a Relationship?

Continuing the somewhat derailing conversation from this thread

My opinion is that the GM should be wary of killing off player’s Relationships. Obviously, sometimes a Relationship stumbles into harm’s way, and when that happens, death is sometimes an appropriate cost for failure. What I feel strongly about is when the GM should put a player’s Relationship in harm’s way. I believe that there are really only three acceptable circumstances for this:
[li] The Relationship (or something having to do with the Relationship, e.g., “the innocent”, “my family”, “the citizens of Townsville”, etc.) is written into the player’s beliefs. By writing the Relationship into their beliefs, a player is telling the GM to use the Relationship as a way to challenge that belief. This doesn’t always have to incorporate putting the Relationship in danger, but that often works.
[/li][li] The players’ failure would reasonably put the Relationship in harm’s way. Preferrably, this should be based on established facts about the relationship. The example I used in the linked thread was the players failing in their roll to incite a riot: the mob of townsfolk becomes out of control and this places a Relationship (who has been established to live in/be in the town – no dragging in someone’s estranged uncle from the other side of the kingdom just because a player failed a test) in harm’s way.
[/li][li] The Relationship is physically acompanying the players. Any time the players are in harm’s way, so is the Relationship.
It’s unfair to the players if the GM endangers their relationships without the players’ consent (i.e., agreeing to a roll when you know the cost of failure, writing a belief about them, bringing them with you).

So, I’ll agree that killing off Relationships is a thing that, as the GM, you probably shouldn’t do without careful consideration of what that means for the players. And I also think that your three bullet points are spot on - those situations are when a Relationship character are in the most danger, because either the player has chosen to make the game, at least for the moment, about that NPC, or the current situation demands that the NPC be facing the same sorts of challenges and consequences that the other characters with them are. So, I’m not going to disagree with any of that.

I don’t think that Relationships should fade away when the player isn’t turning the spotlight on them, though. Relationships are part of the setting, and they have their own agendas and desires, and those usually don’t quite align perfectly with those of the PCs. Sure, they can be assets, or sources of drama, depending on what options you put on them when you buy them, but they don’t just hang around waiting for the PCs to pay attention to them. I’ll often have them show up at inopportune moments for the PCs. Maybe their buddy the King sends a runner with a request for their presence while they’re making preparations for a long sea voyage. Or, maybe their street urchin informant shows up beaten bloody because an adversary tried to get information about the PC out of them. Heck, sometimes a Relationship character might just need a friend to lean on, so they look to the PC for a little advice, or a friendly ear, while being completely unaware of the fact that the PC is being hunted by a death cult bent on revenge.

In my current game, one of the PC’s relationships came looking for help because he couldn’t keep up his end of a bargain he made with a Yugoloth, so the fiends took his wife back to their home in the Lower Planes as collateral. I was able to tie multiple long-term beliefs from the players to the fallout from that NPC coming to the character for help.

Basically, I don’t see Relationships as sacrosanct things that the players get to bring in whenever they’re interested. Spending the points means that the NPC exists, that they’re important to some degree, and that the player, generally speaking, has some kind of access to them without needing to make a Circles roll to find them. They’re still under the control of the GM, though, and beyond their connection to the PC that they’re tied to, the GM can do whatever they want with them, so long as the GM isn’t devaluing the importance that the player paid for, if that makes sense. Also, I think it’s totally fair to wedge them between the Beliefs of different PCs, or to put the PC in the middle of two Relationship NPCs, one or both of which may be connected to another PC.