We had a heart-to-heart talk about his poor attendance.
noun
2.
Informal. a frank talk, especially between two persons.
Origin
1865-70
British Dictionary definitions for heart to heart
heart-to-heart
adjective
1.
(esp of a conversation or discussion) concerned with personal problems or intimate feelings
noun
2.
an intimate conversation or discussion
Idioms and Phrases with heart to heart
heart to heart
Candidly, sincerely, as in We need to talk heart to heart about her coming marriage. This expression is nearly always applied to a conversation of some kind. [ Mid-1900s ]