I think you are confusing the problem with the solution. RyanML pointed out that there is a contradiction in scripture. This would appear to be widely accepted as correct. There is also some contradiction in holy tradition, though not for many centuries.
For Catholics, such contradictions do not represent a problem. We have an apostolic Church, which provides us with proper interpretation of doctrine. However, we do not have a lot of eccumenical guidence, nor has a pope spoken ex cathedra, so we cannot deem our current position to be a moral absolute.
Look at the CDF’s document on civil unions which I linked to before. It is quite forceful, but openly describes the situation as “discrimination”. However, it notes that discrimination is permissible until it interferes with justice. Since secular unions have some taxation and civil rights implications, there is some area of moral ambiguity.
What I find interesting is that many of the Catholics who howl at the suggestion of moral ambiguity in this case often grant themselves some moral latitude with the same teaching. Consider how the Church references the teaching with regards to voting:
vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_20021124_politica_en.html
This is put very forcefully, it is even described as a “fundamental and inalienable ethical demand”. But while I see a lot of enthusiasm for the snippet “between a man and a woman” I see a lot less enthusiasm for promoting the rest. This raises the legitimate question as to rather or not we are motivated by a desire to target and discriminate, which would be sinful, or a sincere desire to defend the family. While we remain selective in our embrace of the teaching, we remain open to the secular accusations of hate.