Having an off day and off feelings

I've been wondering why I got so fed up last night?
On the surface it was because my friends were being drunk idiots and I was genuinely concerned about their safety and angry and how little they were taking care of themselves and the things they were doing and saying.
Also the fact that I was going to get in trouble at home.
Then I thought it was me at my introvert limit. Too many people and too much interaction. Mentally stretched and tired.
Then I blamed myself for being a sober wet blanket, ruining everyone else's fun by being the responsible one.

But now I know that it was because I never really felt the cliche: "to be in a sea of people and still feel so alone", until last night. And because it was amongst some of the people I care most about.

I had never felt that alone in my life.