Fair enough

[ovvpapatya]

It is I who should be apologetic for ever doubting you,” she said.
“Fair enough,” Rovender said with a grin. “Fair
enough.”

Is "fair enough" used in a meaning "i accept your apology" here?

 

[bhaisahab]

It is I who should be apologetic for ever doubting you,” she said.
“Fair enough,” Rovender said with a grin. “Fair
enough.”

Is "fair enough" used in a meaning "I accept your apology" here?

Yes. It implies that the apology is accepted.

 

[Raymott]

It is I who should be apologetic for ever doubting you,” she said.
“Fair enough,” Rovender said with a grin. “Fair
enough.”

Is "fair enough" used in a meaning "i accept your apology" here?

It seems to mean that. But it sounds strange here. I think that is because the first person hasn't apologised yet - he's only said that he should be apologetic.

We would normally say "Fair enough" after a concrete proposition, not a "should" statement.

A: I apologise. Let's try to get along.
B: Fair enough. (Good).

A: I should apologise, I guess.
B: Fair enough. (Strange).

A: Do you think I should apologise?
B: Fair enough. (Wrong).

But I suspect that there's more in the previous dialogue in the original that might make "fair enough" a sensible response - for example if they are arguing over who should be apologising to whom. In this case, "Fair enough" means that the second speaker accepts both the first speaker's argument that it is she who should apologise, and the apology.
"That is a fair enough statement of the situation, and I will go along with it.)