I would like to suggest something that may be
helpful... (not a guaranteed simple "cure")
If a man adopts an attitude and way of thinking such that he considers every woman on earth as being his sister, daughter, niece, etc. - the way he "sees" them can be "regulated" by good intent and self-discipline. And, with continual dedication to this way of thinking - and, with the Lord's help - his "thought life" can become "cleaner" with time - and, actually become more easy to maintain without falling into the "gutter" of over-sexed thinking.
I can attest to the fact that it works wonderfully if you sincerely apply yourself to it while "bringing into captivity every thought" (2 Corinthians 10:5) -
which is much easier to do when it is your sister...
And, that is the key thing - how are you going to think about a particular woman if you convince yourself that she is your sister?
It will not prevent any marriage possibilities in view; however, it may help you "ease into a relationship" with a better balance - not being totally overtaken with a fixation on sex.
If she is saved, then she is my sister-in-Christ. If she is not saved, then she is a sister in the human race. In either case, she is my sister, daughter, niece, etc.