I just did a search and found that my ex does now use GMail.
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 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.
Looks like it's definitely not a personalized result.