Yes. I was thinking Samson. And you are probably right... I thought wife but it says "he fell in love with..." and I don't see that they ever got married so it appears to be an immoral relationship.
Judges 16:4-6
4Some time later, he fell in love with a woman in the Valley of Sorek whose name was Delilah. 5 The rulers of the Philistines went to her and said, “See if you can lure him into showing you the secret of his great strength and how we can overpower him so we may tie him up and subdue him. Each one of us will give you eleven hundred shekels[a] of silver.”
6 So Delilah said to Samson, “Tell me the secret of your great strength and how you can be tied up and subdued.”
I just looked it up too, I thought they were engaged, but the Bible passage does not elaborate. I also think he was incredibally stupid since she tried 3 times to bind him to then tell her the truth was just insane!!!!