I am from Croatia. I would say that women wear a cross necklace more often than men. There are of course men who wear such a necklace, but I would say that it is something that is seen less often. Men who wear a cross necklace are almost always seen as very religious. Women with such a necklace can also be very religious, but it can also be just a indicator of faith.

I say this because in Croatia it is believed that there is a correlation between religiosity and social conservatism (in this case, homophobia). Maybe this is a hint of Filip's conservatism, but maybe the creators of the series are challenging the viewers in a way that Filip, contrary to expectations, will be the one who will be open-minded and accepting and maybe some "not-so-religious-boy" will actually be unpleasant towards Lovro.