Firstly, how far do you trust these fortune tellers? "went to fortune teller (quite accurate)" You yourself claim him to be accurate but how do you know? Personally, I have been foretold by some astrologers on my future that though it gives me a slight fear and cautiousness on things, I choose to brush it off and believe in God then humans(astrologers).
There have been cases I have known that they were foretold negative future and warned not to do certain things but they chose to go ahead with their stuffs and are living successfully and happily together.. No matter what someone foretells, it's how we live that determines if it will come true or not..
Of cos, when someone foretells losing your loved one, it is bound to give you some pain and fear. Should you really want to go ahead with the wedding, you may do your ROM and live apart first then do your customary after 3yrs.. or you may find some rental unit should you want to marry earlier..
Whatever you do, make sure you step into it because you BOTH feel you are ready and committed enough to walk into marriage and not rush into it for the sake of some fortune teller's readings and regret later.. Take care..