My mother told me that my sister was feeling very hurt and missed sharing her feelings and successes with me. After that I made more time for her. Maybe your friend can ask her mom to intervene with her sister. Dear Becky, You are right about pregnant women, they are much more emotional than usual due to the increase of hormones that are needed throughout a pregnancy. You might consider writing a letter to your mom.
Teens are great note writers.
Every time one of my children put their feelings about a problem we were having into a note it had a profound impact on me, for the better. Writing delivers a message without the tonality of sarcasm or anger. It is easier for the reader to process the ideas at their own learning rate. It is a great way to get your point across. Remember to be honest, not rude.