I just thought of something.

Remember the lyrics in WDBCF "they come from boys who like to sit on their ass" ?

What if Rotten Milk is about the dude from that song?

He's lazy and depends on his mother because he got the girl from WDBCF pregnant and left to go live with his mom because he can't even take care of himself and Rotten Milk is told from the perspective of the girl he got pregnant

Again this is just a theory but still i think it makes sense