I won't know what the dad's intentions are to be honest, He was either 1. Sending the hearts as a thank you or 2. Sending the hearts as some sort of answer to the ladies answer or idk, But it might be important to not over think it, Also maybe question your dad about it, I had been through some of that situation, And i just thinked that, They will both divorce because my dad talked with another woman, And I heard my mother talk about it multiple times, When my dad wasn't home or was in a call with her friends, But the same doesn't really go forth, Since it's not really the same deal for you, Have hope please.