Samson sinned greatly, one piece at a time, against his vow, but he was already breaking with God, beginning here:
Jdg 14:1 And Samson went down to Timnath, and saw a woman in Timnath of the daughters of the Philistines.
Jdg 14:2 And he came up, and told his father and his mother, and said, I have seen a woman in Timnath of the daughters of the Philistines: now therefore get her for me to wife.
Jdg 14:3 Then his father and his mother said unto him, Is there never a woman among the daughters of thy brethren, or among all my people, that thou goest to take a wife of the uncircumcised Philistines? And Samson said unto his father, Get her for me; for she pleaseth me well.
Jdg 14:5 Then went Samson down, and his father and his mother, to Timnath, and came to the vineyards of Timnath: and, behold, a young lion roared against him.
Jdg 14:6 And the Spirit of the LORD came mightily upon him, and he rent him as he would have rent a kid, and he had nothing in his hand: but he told not his father or his mother what he had done.
Jdg 14:8 And after a time he returned to take her, and he turned aside to see the carcase of the lion: and, behold, there was a swarm of bees and honey in the carcase of the lion.
Jdg 14:9 And he took thereof in his hands, and went on eating, and came to his father and mother, and he gave them, and they did eat: but he told not them that he had taken the honey out of the carcase of the lion.
Jdg 14:10 So his father went down unto the woman: and Samson made there a feast; for so used the young men to do.
He wasn't allowed to do any of those things.
The 'feast' simply means a 'feast', and is first used in Genesis 19:3, with Abraham and God, and the clean and unleavened, and likewise used in Genesis 21:8. It can mean either, see the rest of the uses in the scripture. In this instance, it was a 'wedding' feast, but this, among the gentiles of Timnath, the Philistines, so it is possible to have been with alcohol, though the context does not specifically say. In either case (grape juice or alcohol), Samson was slowly negating all of the Nazarite vow. His last break was the hair. This is a lesson about slowly backsliding, or leaving God, piece by piece, being overcome piece by piece. It is not a good example, nor blessed of God, even if it were alcohol, or even if it were juice of the grape.
Marriage with unbelievers was forbidden by God, and this is where it all started, with ungodly acquaintances influencing to forget and forsake God, then lust of the eyes, and flesh and pride of life:
See the following for comparison with the Genesis 6:2,4 KJB account:
See Abraham and Isaac in Genesis 24:3,37.
See Esau and Jacob in Genesis 26:34,35, 28:8,9 [comparing to Jacob in Genesis 27:46, 28:1,6 KJB], 36:2.
See Isaac and Jacob in Genesis 27:46, 28:1,6 KJB.
See Jacob and Hamor in Genesis 34:9,14 KJB.
See Moses in Exodus 34:15,16 KJB.
See in Deuteronomy 17:17 KJB.
See Balaam in Numbers 25:1,2,3 KJB.
See in Judges 3:5,6,7 KJB.
See Samson the Judge in Judges 14:1,2,3 KJB.
See the Chronicles in 1 Chronicles 5:24,25 KJB.
See Ezra in Ezra 9:1,2,11,12 KJB.
See Nehemiah in Nehemiah 9:2, 10:28,29,30, 13:23,25,26,27 KJB.
See Solomon in 1 Kings 11:1,2,3,4,5,6,7,8 KJB.
Many “Sons of God” “looked”/“saw” [“saw the daughters of men that they [were] fair” and “took them wives of all which they chose” [Genesis 6:2 KJB]] and "beheld" [Just as did Samson, “she pleaseth me well”, or King David who went after Bathsheba, the wife of Uriah the Hittite and his friend, through covetousness had Uriah killed in action “from the roof he saw a woman washing herself; and the woman [was] very beautiful to look upon” [2 Samuel 11:2, 12:9 KJB] and Solomon who “multiplied wives” and “loved many strange women” and all Israel who took of the “daughters of the land”], and then “lusted and coveted” and so were ensnared being “Vex[ed], Beguiled, To Commit Trespass Against The LORD, Commit Fornication, Eat things sacrificed unto Idols, worshipped idols” [Numbers 25:18, 31:16; Revelation 2:14 KJB]:
Jude 1:11 KJB - Woe unto them! for they have gone in the way of Cain, and ran greedily after the error of Balaam for reward, and perished in the gainsaying of Core.
See also the words of Jesus, as it was in the days of Noah and Lot:
Job 21:7,14, 22:15,16,17; Matthew 24:37,38; Luke 17:26,27; 2 Peter 2:5, 3:3,6.
In the greater overall picture there is a like message and call for the “people of God” also today to “come out” of “Spiritual Babylon” [just as God had done with physical Babylon; Jeremiah 51:9; Isaiah 52:11 KJB] that “great Whore” [Revelation 17:1, 19:2 KJB]:
See 2 Corinthians 6:14,15,16,17,18; Revelation 18:4 KJB.