After/before conveys ordering, not dependency.
Given services A and B, when B has after: [A] this literally means when both A and B are started together, start B after A has started. In systemd’s notion, when both are getting activated, means B will be started once A becomes active. However, the after/before does not mean A requires B to function (in oher words, when B goes down, A must go down too), this is what systemd Requires does, but we do not support it yet.