Why is "story of the hour" ironic?

There are many ironic events in "The Story of the Hour." First of all, we hear that the protagonist's husband has died, which turns out not to be true. Then she feels sad about her husbands death, however, her feelings turn to happiness once she realizes she is finally free. Ultimately, he returns home and she dies because her happiness was suddenly taken away from her - she didn't die because of heart problems, but rather because she no longer would have her freedom she so desperately wants.

The irony in the end is that Louise doesn't die because of joy as the doctor said but actually because of the loss of joy.