Daughter in law wearing cross under the chupah?

I love my son’s fiance and I think we have a great relationship. She is from a Protestant family but is a totally secular person. I am Jewish (my husband is not), our son was raised as a reformed Jew and still seems to enjoy our traditions and identifies as a non-observant Jew.

The fiance has started to wear a cross necklace, and she looks beautiful. However, I have a slight feeling of repulsion at seeing this cross, particulary at the seder or Chanukah gathering. The wedding is coming up and I think there are people in my family who will feel a bit uncomfortable if she wears a cross under the chupah! Should I continue saying nothing about this? Our relationship is very important to me. Is there a light and humorous way to deal with it? Thank you.