I’m gonna play devil’s advocate here about David’s song. If it were written at the time of his divorce he would have been married for 17 years to Tea and known Gillian for 20 so it doesn’t fit either of them. If it were written last year he would have known Tea for 20 years and Gillian for 24 so technically it fits Gillian more. BUT I think lyrics are always open to huge speculation as to who they are about and he could just as easily be talking about someone or something completely different.