You don't fall into love, you crash into it. When you relate with someone, you do so with gusto and passion, and to the depths of your heart and soul. There is no lukewarm or halfway for you in this department.
You give your all, and frankly, there are some people who just can't take it. That's their problem, not yours, and don't let anyone make you think otherwise. You should not have to hold yourself back. Focus on finding someone who delights in your energy rather than being ashamed or frightened of it, and you can find much happiness and satisfaction in your partnerships. Your connections to other people run so deep that you feel very vulnerable, and besides that, your feelings get hurt easily. So early on you must have learned that you need to protect yourself. This self-protection mechanism can make you rather shy and reticent about expressing your true feelings and warmth for another, at least until you feel comfortable. If your early experiences with love and romance were hurtful, you may have receded into celibacy or hermit-hood; just don't let that last forever. Lick your wounds, then come out and try it again. That's where the love is.