In the passage in Shoftim chapter 13, Manoach and his wife speak with an Angel. His wife in verse 6 tells him she has spoken with an Angel. A few verses later, the verse says that Manoach didn’t know he was speaking with an Angel. How did he not know at that point after his wife told him?
Re-read the verse. Manoach's wife told him she met a prophet (איש האלוקים/man of God is a title for a prophet) who looked like an angel:
"The woman went and told her husband, “A man of God came to me; he looked like an angel of God, very frightening. I did not ask him where he was from, nor did he tell me his name."
For this reason Manoach then prays to Hashem to send again the "prophet".