Why did the strong man lose his strength?

Samson, the strong man, fell in love with a woman named Delilah. And the lords of the Philistines went up to the country to see her and said,  Coax him and find out what gives him his great strength, and how we can master him, bind him, and hold him captive . And Delilah tried to find out what gave Samson strength, until finally he told her the secret. He said,  If my head were shaved, then my strength would leave me and I should become as weak as any other man . Delilah then told the Philistines.  She lulled Samson to sleep on her knees and summoned a man, and he shaved the seven locks of Samson s hair for her, and they made him captive. And Samson's strength left him. But the strength was not in the hair, as is so often erroneously said. Samson had taken the Nazirite vow which committed him first to totally abstain from women and from strong wine. The growing of the hair was a symbol of that vow, so that the cutting of the hair was also the symbol of the breaking of the vow.  And then Delilah cried,  The Philistines are upon you, Samson .  He woke from his sleep and said,  I will go out as usual and shake myself .  In other words,  I'm as strong as I ever was .  He did not know that the Lord had left him. We're not as strong as we were.