Not for a lack of interest, or trying, but I just cannot think of what could happen in my black moment short of killing off the love interest (I'm already killing off plenty of characters). What do you guys do to generate ideas? I've considered starting on the rough draft before the outlines done, but I do that a lot and often run aground. Is there a method for forcing ideas out?
Imagine the worst possible thing that could happen to your main character. Then make it happen. If you don't want to kill another person off, how about having the love interest run off with the character's worst enemy?
You could also look to your theme/subplot for dark moment ideas. The dark moment comes about because the MC's approach to problem solving isn't working. The character realizes he's gone as far as he can without changing his approach to life and that's why he's experiencing the dark moment. Theme/subplot is there to teach the MC something about life, something he's been ignoring that affects him in a big way. All this also gives the third act a huge dollop of uncertainty because, going into the third act, MC is trying a new approach to life and no one (MC or reader) has 100% faith it's going to work.