I'm curious about this because I'm never sure myself.
The last few times I've v*ed, circumstances meant that I was alone at the time and I prefer it that way, I hate the idea of anyone seeing me completely vulnerable like that because it's not how I want people to think of me.
Although I can also remember when I was younger, specifically the night of the fp when I was 7, I had a basin with me and I would v*, go clean it up, and then go wake up my parents to give me a hug. (I would love to be that calm about it now). So even though I was totally capable of handling it myself, I still needed that comfort from my family when now, when v*ing is such a trauma for me - I need my family and friends to keep away.