<human>: Can you give me the gist of the text in a nutshell?

So today, I took the subway home with one of my good pals. The bad part kicked in when we were in the train. I almost hit my head on the pole because the train was jerking every few seconds and thankfully my friend managed to catch me before I embarrassed myself in front of people by slinking an arm around me and I just smiled because I didn't have any idea what to do. Of course, I thought he would remove his arm from since we were only friends but he didn't, and it was slightly awkward. But he didn't and I was just quietly in his arms throughout the ride and I might have been a bit too comfortable because I leaned in towards him. At this point, warning bells/cymbals/whateveryoucallit was blaring in my head but because I was a dense person, I didn't even realize what consequences there were.

As much as it was an "aww" moment, it definitely was not, because the fact that he had a girlfriend hit me like a wrecking ball the moment I was in the shower. Boy oh boy, was I in deep trouble.

Fast forward to the next day in school. We avoided each other, because the train incident was uncalled for. 

I'm not the type to break people apart, but the train incident mortified me so badly that I feel like jumping headfirst into quicksand whenever I think of it because it conflicted with my conscience and values so badly.
<bot>: friend saved me from embarrassment, got too comfortable with friend that has a girlfriend, might cause them to end their relationship over a trivial matter, might lose friend