To begin with, I would not try to learn Catholic teaching from non-Catholic websites, especially from websites that are dedicated to tearing down Catholicism (or what they portray Catholicism to be, accurate or not). We should endeavor first to understand each other with as much charity and honesty as possible. Find the common ground. Then, where we find it is not possible to agree, we can draw distinctions.
To give an example of inaccuracy, the site you linked attempts to differentiate between Catholicism and “biblical Christianity”:
Evangelicals believe in Christ for salvation - and in nothing and nobody else, nor do they rely on any merits of our own; whereas Catholics, in addition to faith, base their salvation on the reception of baptism and other sacraments, good works and penance. Evangelicals seek to live a godly life in grateful response to the grace of God; Catholics perform works to merit the graces needed to attain eternal life.
Okay, but what is the actual teaching of the Church? The (Catholic) Council of Trent declares,
And whereas the Apostle saith, that man is justified by faith and freely, those words are to be understood in that sense which the perpetual consent of the Catholic Church hath held and expressed; to wit, that we are therefore said to be justified by faith, because faith is the beginning of human salvation, the foundation, and the root of all Justification; without which it is impossible to please God, and to come unto the fellowship of His sons: but we are therefore said to be justified freely, because that none of those things which precede justification-whether faith or works-merit the grace itself of justification. For, if it be a grace, it is not now by works, otherwise, as the same Apostle says, grace is no more grace.
(Session 6, Decree on Justification, ch. 8)
Now, this is a teaching that is stronger than even many Evangelicals would feel comfortable affirming. The Roman Catholic affirms that justification is entirely by grace apart from any merit on the part of the man, and he can stand together with the staunchest of Calvinists on that point. The problem is that the Just for Catholics author has failed to clearly define what he means. Is receiving the sacraments a work? Is it necessary to obey God’s commandments to enter into heaven? Can justification be lost? Is faith not a work? There are suppositions behind these questions and more that have to be treated before we can accurately evaluate the differences between the two positions.
Before you reject your boyfriend’s faith, I would make a good-faith effort to understand what his faith actually is. It is not enough to say, “I believe this, and you believe that, and that’s just the way things are.” It is necessary to understand the Catholic teachings, properly understand your own beliefs and then evaluate the similarities and differences. By the fact of you making this thread, it is clear that you have an interest in working things out, so this will not be a worthless process. At the end, if you decide things can’t work, at least you will be better for what you learned in your period of discernment.
As for whether interfaith marriages can work, I say it is possible. Even between two Catholics, it is probable that one will be more devout than the other and there will not be uniformity of mind or spirit on every last thing, but spouses have to work together regardless. Between a Catholic and a non-Catholic, a good marriage is possible provided that there is enough common ground for you to be able to work tother toward your common goals, and provided that the non-Catholic will not be an obstacle to the Catholic upbringing of the children.
I see a few possibilities. You might decide that the Catholic faith was right all along after all. That would make things very simple. Second, you might decide that you cannot subscribe to the Catholic faith, but that the Catholic faith is acceptable for your spouse and your children. You might even come to the conclusion that the Catholic faith is, when it comes down to it, just as good as the beliefs of any Protestant denomination. “Sure, the Catholic Church has silly rituals and funny hats, but they still believe the Gospel.” I have certainly met plenty of Protestants who believe this way, and I believe it is a tenable position to hold from a Protestant perspective. I think marriage would be possible in this case. On the other hand, you might discern that the Catholic Church is the apostate Whore of Babylon, the Pope is the Antichrist, and that the Catholic faith is demonic, pagan superstition. In that case, I think you would have to admit a marriage is not possible.
In short, you will have to find what agreement you can arrive at and whether that is sufficient to build a successful marriage on.
