There is a way to differentiate the things that happen to us because we had to go through them, and the things that happen to us because we did nothing to avoid them, and that is by asking ourselves the question: was it necessary for me to go through this? If so, we can blame karma, but if it wasn't necessary, if we could do something to prevent it and we didn't, it's just our own fault.

In the end, the very concept of karma is supposed to aim for us to be more responsible for what happens to us, not less.