What was Apollo the gods weakness?

In the beginning it seems he was a god of avenging evil, often getting away with acts either outrageous or severe. A few examples;

Killing the Python in the oracle Delphi, a sacred place, and then calling that place his own.

Killing Marsyas who the god Apollo felt threatened by as a musician and entered into a contest with, killing him when he lost.

As lover of Coronis, when he received news she was entertaining a male guest, he killed her and from her dead body the baby Asclepius was born.