I think it's just as likely that this is song is a fiction. If it's not a fiction, it's likely that "Davey" is a pseudonym. If it's not a pseudonym, then it could be any young actor also named David. It's certainly not uncommon for young women to have relationships that they regret, i.e. becoming too attached to someone who turns out to be a cad to the nth degree. This song depicts one of those such instances.
I think it's just as likely that this is song is a fiction. If it's not a fiction, it's likely that "Davey" is a pseudonym. If it's not a pseudonym, then it could be any young actor also named David. It's certainly not uncommon for young women to have relationships that they regret, i.e. becoming too attached to someone who turns out to be a cad to the nth degree. This song depicts one of those such instances.