"Of course"/ "What do you expect?" / "I told you so"

Interesting examples. They sound negative if you say them in response to something negative, like "What a waste of time!" but not if you say them in response to something positive, like "That was fun!"

It sounds like your friend is hearing a lot of negativity and reflecting it back to you, which is not what you want.

Now, were those simply poorly chosen examples, or do they really show what is happening?