Lyric discussion by cupswithoutlids 

Cover art for Phillys Magic lyrics by Woodbine Hotline

It seems like he's frustrated with a relationship because he's at a different place in his life than the girl is. Like she's really immature and changes her mind a lot and he goes crazy trying to deal with it.

But ultimately, as the chorus suggests, he finds out that he doesn't need that girl to be happy because he's happy with himself.