There is only One Church and One Body made up of all who believe in Jesus Christ.
Those who suggest that a Catholic-Protestant should not marry or could not marry because of differences or 'compromise' are probably too immature to marry anyhow...since 'compromise' is the inherant essence of marriage.
Scripture says, a spouse is no longer his/her own, but his/her spouses' as well.
Being from one denomination or another does not now nor EVER has disqualified marriage between believing christians and those who emphasize the differences do so as the teaching of MEN, not GOD and run the risk of running CONTRARILY to God's will just as Mirriam and Aaron did when they criticized Moses' marriage to a black woman.
God dealt with both Miriam and Aaron swiftly.
The Scripture does NOT even suggest that one of one Christian beleiving denomination cannot nor should not marry one of another denomination.
In fact, according to scripture, such a notion is completely absurd.
There is ONE BODY and ONE CHURCH.
If you cannot compromise then certainly DO NOT marry, but not because it is wrong to marry outside of your denomination, but because you are too immature in Christ or too inflexible in person to be married at all.