Jed, trust me, serious depression can easily be hidden, especially if your family, friends, SO's whatever don't really want to see it. Been there, done that. My family wouldn't even see it when I tried to tell them, until the night I OD's on over the counter stuff because I was so angry/isolated/unbelieved, etc.

Then, they got mad at ME for taking all that stuff instead of talking----I HAD been trying to talk for months but nobody would listen.