Things in my own life that make me want to write about them are often things that are unresolved. And I use writing to figure them out.
Memoirists Meredith Maran, Dani Shapiro, Ayelet Waldman, Kate Christensen, and Nick Flynn speak in a YouTube video about why they write about their own lives, and the best/worst things that happened to them as a result of writing a memoir.