That use of
と should be conceptualized as “with”, and not “from”.
“Xと離れる” is “to separate with X”. Since you can both separate with and separate from something, both
から work here (albeit with the subtle difference between “separating with” and “separating from” something).
“Xから聞く” is “to hear from X”. Replacing this with
と would change the phrase to mean “to hear with X”, as in “I heard it with her (彼女と聞いた)”. Alternatively, the
と can function as a quotative particle, where “Xと聞く” would mean “to hear that X”, as in “I heard that she is a girlfriend (彼女と聞いた)”.
- In the sense of either “accompanied by” (I will go with you) or “in some particular relation to” (She agreed with me), but not “by use of” (Cut with a knife). See also: Confusion with Japanese particle と in its multiple uses.
- Verb as used without object. (When used with object, the verb is 離す)
- I understand that in English “separate from” is the standard preposition choice here. I just wanted to illustrate the から/と difference. “To separate from my parents (親から離れる)” connotes a starting point in space/time from which I am the one moving away, while “to separate with my parents (親と離れる)” feels more like a mutual split where I am not necessarily the primary mover. (To complicate things a bit, since
と can also mean with as in “accompanied by”, you can say for example グループから親と離れる to mean “to separate from the group with my parents”.)