Confusion

Once-in-a-lifetime.. something comes up on your mind- a thought, an idea, or even feeling- and as important as it is to you you hold onto it and give it a good time thinking. Should you continue with it?Or is it better to just turn back and forget about it? Some people would say "well, if it's something related to your future ,as in something financially or like a lifetime decision, then you gotta think thoughtfully with your mind. But if it's not that,you can follow your heart. However,sometimes in some things,this just won't work because every aspect has advantages and disadvantages and the disadvantages might outweigh both your mind and your heart's point of view. At the end what should you do if you want to turn back? How,specially if it's related to your heart Just like loving someone not good for you? And then you think "do you really really love him? do you really think he can be your future husband/wife? iIf you said " No..BUT", the mind would say "No BUT'S! If it didn't work out, you will lose him forever and you know it. What if he hurts you? It'll leave a mark forever. You already said no so don't risk it. Meanwhile the heart would say" but you love him?maybe this can help you two build a future together. But he makes you happy? But you feel jealous every time you see him with someone else? But you're always thinking and worried about him?" And at the end, the mind just keeps on being stubborn and the heart in a case of "in-love-but afraid" and you just end up being confused.