I didn't because

Spotted on Facebook:
AA:Sometimes I'm glad that my stuff is not generally read widely, even if that makes me a bit of a coward.
BB: I did not "like" because I think you're a coward, AA, but because I totally understand that.

Even with the "but because", it took me a few reads to resolve the ambiguity: "The reason I "liked" that is not that I think you're a coward" rather than "I did not "like" that and the reason is that I think you're a coward".

I think in speech the distinction would be clearer.

Also, of course, normally when someone says "I didn't do X because Y", you have the knowledge that they did, or didn't do, X. On Facebook, you can't tell - on someone else's post - whether the writer of a comment is also a Liker of another comment.