hard feelings - typical idiom meaning bad feelings (it is usually said to try to make sure you did not mean harm) heart feelings - are you aure it was not "hurt feelings"? again, this means bad feelings, something happened that hurt me. Also, there is a word, heartfelt, which means something that is very deeply or sincerely felt "My friend's father died and I am filled with heartfelt sympathy for her." Finally, a writer might use the term "heart feelings" to imply that the feelings were ones that warmed your heart (cheered you up, made you feel good). It is not a common term.

'Hard feelings' is the correct idiom. You're guess was correct! It's usually said like this- "No hard feelings?" and the reply is usually "No" ^_^