Hi
I believe the difference between these is the following:
You (or another person) can be fine with something like a plan, an idea, a situation. For example: "I'm with with John's plan to reduce overtime payments." And: "We're both fine with the arrangements you've made for the Christmas party."
Whereas, something can be fine for something else. For example: "This simple contract is fine for the time being. We can always edit it later." And: The design on the packaging is fine for this type of product."
Does this answer your question? Hope so.
Ronnie