I don't think I was fairly treated, but “then” that's life, isn't it?

Question

What is "then" here?

I can hardly understand the "then" here.

"Then" means at a particular time in the past or in the future.

Answer 1

I wasn't treated fairly, but then (again) it's life.

If you think about it more or from a different perspective, it will make more sense. If you believe that the world we live in doesn't always seem to be fair, then you, who were treated badly, is a just another example of this belief.