As a traditional astrologer, to give the best answer to this question I would want to see the whole chart so I could evaluate the strengths of the Ascendant and seventh house rulers, and see if they aspect each other.
From what you’ve written, however, it’s pretty obvious that you have the ability with a very strong Saturn to filter out inappropriate partners; it’s just that with the idealism of Neptune influencing your emotions (Moon), you choose not to use that filter and that’s why you would run into trouble.
What I would suggest is working on developing your intuition (Neptune/Moon) and following it. Your Saturn should be able to help you exclude partners who will trample on you, though with the square it won’t be easy. It will be worth it, because with the very strong Venus, you definitely have the ability to attract someone who will treat you right.