If this young woman believes in this type of use of holy water, it does not surprise me that she dates a pagan. Indeed, if that is her idea of Catholicism and the use of sacramentals, she may find much in common with his faith if his is one that uses and believes in magic and witchcraft.
As a pantheist, I am a marginal member of the pagan community, and belong to some pagan forums. I have shared here at CAF before how similar much of the practices are. I was raised Catholic and saw much superstition and magical understandings and uses of statues, medals, and other sacramentals. It was, unfortunately very common, where I was growing up.
While official teaching may be far from such magical and superstitious use, I fear that such practices as mentioned above are sadly common. Indeed, it makes many Catholics feel at home in the world of magic and witchcraft and many pagans feel free to borrow and use the sacramentals of Catholicism.
I am not sure, in a Church so large and global, how proper Catechesis might be done to counteract this type of belief and behavior. I had a friend raised Catholic in France who spoke of the same running rampant in her country.
I am sharing what I hear and read in posts from Catholics and Catholics turned pagan, and pagans dabbling in Catholicism. Many people do not understand or practice any material difference in the use of pagan talismans and Catholic sacramentals.
People who know better can do their faith and fellow church members a service by teaching the proper theology and use of these items.
I fear a great deal of mischief takes place.
I certainly know it has in my life, and, indeed, was one of the things that made me flee Catholicism. I am now in a religion that does not use such images and items, not because they are inherently wrong, but because there is so much tendency toward misuse and misunderstanding, that I found it to outweigh the benefit in my life.