I lost the ability to "follow my heart" roughly at age 18. For most of my high school years, romance and dating were out of the question, due to the relentless bullying I was experiencing. Plus, to date in my high school, a guy had to have a car, which I didn't have. So, all that made me very jaded and bitter when it came to romance.
My senior year, I softened up a little, after some positive experiences the summer before, when I worked at a park district pool; close hugs were the maximum I got, but that felt like a gold mine compared to nonstop rejection earlier. That school year, there was a girl in class who showed romantic interest in me, through playful banter during class (the teacher had a very liberal talking policy) and talking to me outside of class. So I asked her out. But there was a problem: when I was telling her where I wanted to go, I had to tell her I didn't have a car. I was willing to pay for a taxi, but as soon as she found out I had no car, she rejected me.
Somehow, that flipped some sort of a kill switch in the part of my brain that controls romantic feelings, and ever since then, I never had a crush on a girl who I wasn't 100% sure liked me back. Even more so, when a girl who liked me stops liking me, any romantic feelings I have for her shut off automatically. In fact, when I tried my luck at dating my freshman year of college, I automatically started liking a girl who I thought was romantic interest, and instantly stopped liking her when I found out that it was really friendship interest.
So all in all, "following my heart" is a moot point. In fact, back in 2005, I confided to a co-worker about a girl I was dating at the time, and the co-worker told me "do what your heart tells you". I responded with: "well, it's telling me to cut back on saturated fat, but how is that relevant to my dating life?". Similarly, when someone talks to me about chemistry (the romantic kind), I come back with "the only chemistry I believe in is C2H5OH" (the formula of alcohol).