Pope Pius XI explains in his encyclical Casti Connubii:
They, therefore, who rashly and heedlessly contract mixed marriages, from which the maternal love and providence of the Church dissuades her children for very sound reasons, fail conspicuously in this respect, sometimes with danger to their eternal salvation. This attitude of the Church to mixed marriages appears in many of her documents, all of which are summed up in the Code of Canon Law: "Everywhere and with the greatest strictness the Church forbids marriages between baptized persons, one of whom is a Catholic and the other a member of a schismatical or heretical sect; and if there is, add to this, the danger of the falling away of the Catholic party and the perversion of the children, such a marriage is forbidden also by the divine law."[62] If the Church occasionally on account of circumstances does not refuse to grant a dispensation from these strict laws (provided that the divine law remains intact and the dangers above mentioned are provided against by suitable safeguards), it is unlikely that the Catholic party will not suffer some detriment from such a marriage.Whence it comes about not unfrequently, as experience shows, that deplorable defections from religion occur among the offspring, or at least a headlong descent into that religious indifference which is closely allied to impiety. There is this also to be considered that in these mixed marriages it becomes much more difficult to imitate by a lively conformity of spirit the mystery of which We have spoken, namely that close union between Christ and His Church.
Assuredly, also, will there be wanting that close union of spirit which as it is the sign and mark of the Church of Christ, so also should be the sign of Christian wedlock, its glory and adornment. For, where there exists diversity of mind, truth and feeling, the bond of union of mind and heart is wont to be broken, or at least weakened. From this comes the danger lest the love of man and wife grow cold and the peace and happiness of family life, resting as it does on the union of hearts, be destroyed.
"Occasionally"? The Church FREQUENTLY granted dispensations, even in Pius XI's day. But, Pius XI's condemnation (that is what it is) caused good people like my parents to be married in the rectory of Annunciation Church in Houston in 1944. My father later converted to Catholicism, in spite of this humiliation, and mom and dad died, 48 years later, within a year of each other, still married.
ACAC, as long as you and your spouse are aware of the issues involved in marriages involving two people of different faiths, there's nothing "bad" about your marriage.
Max, you know very well that the Church's attitude toward mixed marriages has changed, significantly. That's for the better.