I Am Trying to Break Your Heart

After plenty of time to think this song over, it seems to me that it's a story of what takes place over the course of one desperate night in the life of the protagonist. Each verse is an in-the-moment account of what is going on through the protagonist's head. Each moment is summed up by a generic question asking himself what he was thinking when he decided to do what he is doing in that specific moment. No matter what happens, he's insecure about it. I'll break it down as simply as I can:

1. Pretty straightforward. He starts off with a night out in the city, begins drinking heavily, and starts to wonder why he allowed his previous relationship to fall apart. In his drunken state, he is certain that he knows what he wants--her back in his life.

i am an american aquarium drinker i assasin down the avenue i'm hiding out in the big city blinkin' what was i thinkin' when i let go of you

2. He shows up randomly at the ex-girlfriend's place, apologizes/says whatever it takes to attain forgiveness, tells her he seriously wants to be with her and that it hurts to not have her in his life. He may actually believe he means what he says.

let's forget about the tongue-tied lightning let's undress just like cross-eyed strangers well this is not a joke so please stop smiling what was i thinking when i said it didn't hurt

3. He successfully gets the girl to sleep with him, and below are the thoughts going through his mind as they have sex ("take you from the inside"). He sees what he's still attracted to as they're having sex, but as soon as they finish, he begins to get scared and blames drinking for his actions. He expresses his self-doubt by thinking, "What was I thinking when you said 'goodnight'?"--meaning that when she tried to tell him goodnight, he wishes he would've listened to her rather than continuing to try and get her to sleep with him.

i wanna glide through the brown eyes dreamin' take you from the inside baby hold on tight well you were so right when you said i've been drinkin' what was i thinkin' when you said goodnight

4. In the aftermath of the sex, he can't run out right away, and feels that he must stay through the night and do everything a good lover would do (cuddling, holding, whispering sweet nothings). However, his insecurities ("what was I thinking...?") and embarrassment ("bury me now") about what has happened are starting to take over, and he's ready to run out the door as soon as the sun comes up.

i wanna hold you in the bible black pre-dawn you're quite a quiet domino bury me now take off yer bandaid 'cause i don't believe in touchdowns what was i thinking when we said hello

5. This is when he begins to transfer his insecure thoughts to thoughts that place the blame on her, all in preparation to justify to himself the reason to again run away from the relationship. He's convincing himself that it's her fault that she doesn't love him so strongly anymore (although it's implied that it's most likely his own fault). It's also her fault that sleeping with her didn't turn out as magical as he had drunkenly thought it would, even though his own negative thinking and drunkenness are what made it less magical. Once he's succeeded in convincing himself of these things, then he can ask himself, "What was I thinking when I let you back in?" and answer it the way he truly wants to be able to answer it.

i always thought that if i held you tightly you would always love me like you did back then then i fell asleep and the city kept blinkin' what was i thinkin' when i let you back in

6. However, convincing himself of the above rationalizations doesn't work perfectly, so he has some guilt. Deep down, he knows what he did and how it impacted her.

i am trying to break your heart i am trying to break your heart still i would lyin' if i said it wasn't easy i am trying to break your heart

i am trying to break your heart i am trying to break your heart i am trying to break your heart i am trying to break your heart

7. The last bit, to me, makes the story come full circle. He now drinks less, but still feels remorse for having lost the girl. However, he learned his lesson after the last big drinking night and won't do that again. Unfortunately for him, he's still telling himself that he's the man who loves her. Most likely, by now she wouldn't have anything to do with him anyway. So he's stuck, just drinking, hiding out, and unable to move on with life.

Disposable Dixie-cup drinking I assassin down the avenue I'm hiding out in the big city blinking What was I thinking when I let go of you?

loves you I'm the man who loves you

As one previous poster mentioned, the beginning of the song is pure chaos, which fades into the structured song/story, which fades back into utter chaos at the end (as the protagonist goes back into hiding after the emotional chaos he's created). IMO, this provides a perfect feel for the insecurities and emotions portrayed in this song.