Can friendship be lost after it is gained?

Question

Once I gained friendship with one of my companions, can it be lost? If my approval rate with one companion is at 100, can it be lowered if I do actions that are disapproved by the character?

Conversely, if my approval rate is -100, can I redeem myself or is it too late for that?

Answer 1

Yes, friendship can be lost after it's gained, and friendship can be reforged (to a point, see below) after it's lost.

Getting to +100 does not mean you're safe and can say anything you want around your companion. If you say something disagreeable, your companion's approval will go down.¹

Getting to -100 puts your companion into crisis mode, and you get one chance to fix it through a dialog:

• If you navigate correctly, you'll gain approval and your companion will stay.
• If you don't, your companion will leave for good.

Similarly, if your companion enters crisis mode again by hitting -100 a second time, that's it: they'll automatically leave.

Note that this was "fixed" in Dragon Age II: companions won't leave (-100 just corresponds to "rivalry" instead of "crisis" or "hatred"), and once you hit 100 friendship or rivalry, it'll stay locked for the rest of the game.

^{Note 1: this is in part why you don't need +100 to initiate a romance: just +80 to +90 (depending on the companion).}