It might end up making you more committed to and active in your Catholic faith than ever. A study was done recently by a Church-related agency on the level of religious commitment among couples. It found that a high incidence of couples who were very engaged in the life of their parish were those in which one of the partners had been a member of another tradition of Christian faith and, over time, had become Catholic.
Why would that be? Perhaps because the fact that there were some differences there made each of the spouses more attentive to their faith and practice. Perhaps because through dialogue and seeking ways to pray together, a shared faith life came to mean all that more to them.
It’s easy to imagine the situation of being an interchurch couple having a very different effect, too. For example, instead of talking about their commonalities and differences, they might just avoid the occasion of possible tension, or, worse yet, they might both became inactive Christians so as to avoid “going there” altogether.
Generally, the Catholic Church sees marrying a member of your own church as the best and easiest way to go simply because, over the long haul, marriage is challenging and you need all the supports that you can possibly have going for you. A shared faith is a very strong source of support and strength. However, it’s not difficult to see either that if a Catholic background is something both parties bring to the relationship that they might just take it for granted and not bring much energy and focus to deepening their faith understanding. They might just spend the rest of their lives on a “plateau”, going through the motions, etc.
All of which may explain those survey results. Maybe those who were once interchurch couples but are now both Catholics are active in their parishes because for them membership in the same church was a positive, conscious choice made at some cost, so they do not take it for granted and work at keeping their faith life alive and active.
So you just never know where your dating and possibly marrying a Christian from another church might take you.