Well, poem #2 shades the meaning of #1 for me. #2 suggests a bar fight involving the guy in #1.

For number #7, in part because of the context (in the bar), and the gender pairing between #1 and #7, it's seems that 'what happened' was either romantic or sexual. With the girl it is easy to think of rape or even consensual sex that she regrets.

Because of the sequence, or that you begin and end with the 'drinking to forget', I have to see them as connected, so that both are drinking to forget the same event. I doubt that a man (or maybe most men) would drink to forget random consensual sex.

Of course, it could be a couple that broke up romantically, or agreed to a divorce. Again the context of a bar and the hook up scene that goes with it suggest sex to me, though.

Gender is such a straitjacket. If I were reading this as a single stanza, with a one word change (man/girl), I absolutely would think of a plethora of possibilities for the guy to be forgetting (bad business deal, for example), but with the girl it would probably be limited to sex or romance. Ridiculous, I know, but even though I know it's ridiculous, I'm still filtering the world that way, to some extent.