Subtext of "fair enough"

Solution 1:

"Fair enough" is an even-handed acknowledgment that the person on the other side of an argument has made a valid point. It is a concession of sorts, and sometimes may mean that the person saying it wants to drop the discussion, but that is by no means a requirement.

Speaker 1: You said the dinosaurs were killed by an asteroid, but there is mounting evidence that volcanic activity in India may share the blame.
Speaker 2: Fair enough.

Here "fair enough" means Speaker 2 is merely conceding that what Speaker 1 is saying may be true. It would not express impatience or a desire to discontinue discussion unless Speaker 2 used additional dialogue to make those things clear.

Note: The expression itself is not at all negative and certainly not offensive. In fact, it is often used precisely to avoid giving offense.