I am unaware of whether my ex uses GMail or not. We were in school when we met and had uni email addresses.
I also searched through the contacts and conversations for both my GMail account and my girlfriend's (she consented, of course) - result: in neither did my ex show up.
I have found that the results change when you are and it will promote things that you have search for and emailed about before.
I am unaware of whether my ex uses GMail or not. We were in school when we met and had uni email addresses.