It's kind of ignorant to think there must be some "reason" for his suicide. While that may be true occasionally, the only "reason" behind most suicides is clinical depression, a mental illness. "Why did he do it?" is a question that probably doesn't have an answer, so expecting that the answer will someday be revealed seems naive.
Incidentally, this Lydia character introduced today looks exactly like someone close to me (cartoonified, of course) who killed herself a number of years ago. Now there's an unpleasant reminder I wasn't expecting with my daily dose of QC. . . .