Heart-to-heart (adverb)

1. In an open, honest, and sincere manner.
2. In a serious and intimate conversation.

Origin:

From the literal meaning of 'heart to heart', meaning directly from one person's heart to another's.

Examples:

1. They talked heart-to-heart about their concerns.
2. The manager spoke to the team heart-to-heart about their performance.
3. He apologized heart-to-heart for his mistake.
4. The couple resolved their issues by communicating heart-to-heart.
5. She advised her friend heart-to-heart about the difficult decision.