This person is not a Sikh when they are bowing down to Guru Granth Sahib Ji. They're going around Guru Granth Sahib Ji and saying “you are the focus of my life” but they're not following Guru. Why are we making them do that? Just take them to a registry marriage and get them married. So, you can have an interfaith marriage, but you can't have an interfaith Anand Karaj. The Anand Karaj is a ceremony between two Sikhs and the Guru, two Sikhs commit to the Guru together during an Anand Karaj. Have your interfaith marriage if you want to. It's your choice, but don't try to force the other person to go around because you want to have a Sikh marriage.