I would be very wary of the relationship and the situation. Because of their young ages, there is still a great danger of your daughter becoming indoctrinated. If you try to pull her away, it may drive her closer. She needs to be educated in the dark side of JW life and not be roped in with the "lovebombing."
My ex-wife had a crush on a JW boy in high school. He was far from the best example of a JW brother. He got in fights, spent alot time in the dean's office, slacked off in school (why bother the end was coming in the mid eighties), drank alcohol, and regularly got drunk. He hid this from the congregation. However, my ex had self esteem issues and suffered through the death of a close family member. He befriended her and she became interested in the JWs. He started a study with her at school because her parents were opposed. They are from a non-christian belief system. A young sister took over the study for awhile and he became the congregation hero for finding a "sheeplike" one. They studied at school during her lunch period without her parents knowing. She was ripe for the pickings. She had severe emotional issues with the death and the mental abuse in her family. Her family life was very dysfunctional and unhealthy for a young woman. She fell for the life, hook, line, and sinker.
My unbelieving family was attending the same hall as the her and the double life brother. He offered me a Bible study and my parents encouraged me to study with him. I liked her and started to study with him to spend more time with them. Ultimately, she dropped out of college, we got married, had 2 kids, and spent about 25 years in WTland. I had learned TTATT (the truth about the truth) and it cost us our marriage. However, I am finally out but my kids (young adults) and my parents shun me and will not have anything to do with me. They are uber dubs but I have hope that one day they will wake up and see the WTBT$ for what they are. BTW, the double life brother is now a DFed raging alcoholic who destroyed his marriage. However, most of his kids were not baptized so he still gets to spend time with them. How ironic.