Belief systems need not be based on religion. Some couples experience strong chemistry through their shared beliefs in living, environmentalism, vegetarian diet, or other principles that do not require religious views as a basis. On the other hand, some couples practice and share traditional religious views.
When couples have different religious beliefs, one may ask the other to convert, but it’s still possible to maintain spiritual, romantic chemistry despite differences in faith. Interfaith marriages can still be successful if both partners are willing to make room for each other’s religious views.