It is possible to express that sentiment in idiomatic English, but there is not a particularly common phrase that says everything you're trying to say. The closest would probably be something like for the sake of our friendship or to keep the peace. You would use these when you were giving in, but making it clear that it was only for the asker's sake.

For example:

I hate sports, but for the sake of our friendship, I'll go to your game anyway.

 

You had your allowance already, but just to keep the peace I'll give you another five bucks.

It is possible to express that sentiment in idiomatic English, but there is not a particularly common phrase that says everything you're trying to say. The closest would probably be something like for the sake of our friendship or to keep the peace. You would use these when you were giving in, but making it clear that it was only for the asker's sake.

For example:

I hate sports, but for the sake of our friendship, I'll go to your game anyway.

You had your allowance already, but just to keep the peace I'll give you another five bucks.