The perfect tenses, all of them, are used to express actions that have ocurred for a period of time. It’s about continuity. The present perfect refers to a situation initiated in the past – and has lasted for some time- whose effects are important in the present. So, she was talking about her British accent and she used her formers partners accent to reinforce why she uses it instead of her american accent. To me, it’s not about her being with a British guy but about the way she speaks.