I had a friend and we had been TTC at the same time and it was part of our friendship since we both struggled with infertility and confided in each other (she was distraught and had a melt down when her sister had an abortion because 'all she wanted was the chance to be a mother').
She moved away for 6 months, got pregnant and moved back, then one night called me to say she was in the hospital with a suspected miscarraige and I dropped everything to rush to her side.
Stayed in hospital over night while she had tests and got the all clear for miscarraige and then as we left she dragged me to the bar, ordered an alcoholic drink (just 10 minutes after leaving hospital), popped a pill which turned out to be ecstacy and when I in my shock asked 'what about the baby?' she said 'if the babys messed up from it I'll just abort'.
Blew my mind, its like the girl I had known for years was unrecognisable - I dont know what happened in those months but a different girl came back from the one that left.
I was still TTC and honestly it was just too painful too watch so I distanced myself, she did invite me to meet the baby (who was miraculously ok) after the birth but it turned into a party with drugs and I left - drugs are not nor ever have been my thing (hell I dont even like popping paracetemol lol).
In general Im pretty laid back though, Im not one for drama filled friendships and falling out over nothing so theres nothing else I can think of. I can see you every day or not for 10 years and Ill still treat you exactly the same level of friendship as long as you havent done a complete 180 in personality.