From my perspective it seems like he's dealing with his inner emotions or his anxiety.
There's a spirit in Montana and in your chest, a soul
Oh what a soul
He's implying that there is an emotion within everyone and everywhere. So when he attempted to approach this girl, he was confronted by his anxiety and then he succumbs to it by leaving her without making any approach.
From my perspective it seems like he's dealing with his inner emotions or his anxiety.
There's a spirit in Montana and in your chest, a soul Oh what a soul
He's implying that there is an emotion within everyone and everywhere. So when he attempted to approach this girl, he was confronted by his anxiety and then he succumbs to it by leaving her without making any approach.