The church's position on marriage and the sacred act wherein humans, in reflection of their status of images of God are empowered to make life in their own image has been clear for a very very long time. Its clear in the New and Old Testament, the Church Fathers were also very clear on the subject.
You can certainly disagree with them, but that will generally just place you in error and contradiction with clear scripture.
Again, you can choose to live how you want and this is not the place to litigate the issue.