The confidant receives knowledge without always receiving a choice about carrying it.

Being told something makes you a carrier whether or not you wanted to be. The knowledge arrives, and with it an obligation, a weight, and sometimes a conflict with someone else you care about, none of which you agreed to in advance. Confiding is a gift that is also an imposition.

So ask before you unload something heavy: whether now is a good time, whether they have room. It costs one sentence and changes the whole exchange. And if something has been placed on you that you cannot carry, saying so honestly is allowed, and it is kinder than holding it badly.