Leslie, I just saw your last update. I'm so sorry to hear the sad news. I'm sure all of you are heartbroken, not just her. We have very good friends who found out they couldn't have children after a few years of trying. We had a mutual group of friends at the time who were all the same age, all having babies. They found it so hard to be around all the pregnancies and babies, that they started avoiding social interactions with those friends. She felt terrible telling me her wish to stay away from them, but I was a safe sounding board since I was also childless. Like you said, she couldn't understand why a healthy, happy, well-adjusted couple couldn't have kids, but drug-using teens could pop them out every year. It's crazy. They started down the adoption road initially, but it didn't feel right. They eventually widened their circle of friends and activities, and they have a happy, busy life, but I know it's a sadness that stays with them. I know they would've been super parents.
On the other hand, I had a neighbor who was told as a young woman she couldn't have children. Lo and behold, at 39, she found herself pregnant, after she and her husband arranged their life around a childless plan (their house had no room for a nursery, no yard, career choices were made, etc.). It was a complete shock, but she had a healthy boy and he's nearly 4 now.
Since I chose not to have children, I can only try to imagine the sadness one feels in this situation, but having been close to my friend when she faced it, I know what you're feeling as someone who cares about her.