So GnuPG 2.1 fucked up your secret keyring...
Yes, that's what it does :(
Luckily there's a fairly quick fix:
get a console and:
cp -rv .gnupg gnupg.OLD
gpg -export-ownertrust > otrust.txt
gpg --import .gnupg/secring.gpg
gpg --import-ownertrust otrust.txt
rm -r gnupg.OLD