I have a longstanding friend who has been teetotal for the whole time that I've known her. She said that she doesn't like the taste and it's never been a big deal.
In the last six months another friend and I have noticed that she is often drunk towards the end of an evening. She doesn't order drinks when we're out and still refuses alcohol if offered. But she finds an excuse to disappear briefly and is drunk shortly afterwards.
I have no idea how or whether to say something. Does anyone have experience or advice? It's the secrecy that's concerning.