Donating boner marrow is not that big a deal. She'd have a little pain in her lower back for a few days and would regrow all her marrow in 4-6 weeks.
"bone" marrow
For you, perhaps no big deal... but she might have risk factors that make such a surgical procedure much more dangerous... Many people have a history of reaction to anesthesia which predisposes them to greatly increased chance of sudden death during even routine procedures. There are a number of other conditions that would make even a routine surgery very risky... My point is we don't know the facts, just a very one sided spin. Maybe she is cold hearted, but we just don't know. I'm not judging her based on that.