Why have I found it so hard to open my heart?

There's this common saying that everyone wants to love and be loved in return, which I believe is true, and over the years I've seen this play out in the lives of many and how love has changed the personalities of those who found it. I've once given it a try and ended up with huge bruises on my heart, which refuse to heal after several years of living with the pain of heartbreak.

I guess the pain I experienced from the last relationship made my heart construct a great wall around itself in order not to fall victim to such again, but like we all know, the heart can't really hold grudges for long, and I guess this was why I've on several occasions tried to break the bond of the vow I made, but it seems impossible.

Yea, on the day of my first heartbreak I vowed never to enter into a relationship or fall in love again, but after years of staying true to that, I'm gradually losing the grip on that, but each time I approached a lady with a mindset to build a friendship that might lead in that direction, in the next minutes after a pleasant discussion with her, when I'm alone, I tend to come back to my senses and never call her again.

And it happens to be someone who stays around my vicinity, so I just try as much as possible to avoid her till the mutual friendship we were trying to build fades away. Some days I feel it fulfilling knowing that I've been able to flee from a prospective heartbreak, but I guess like everyone around me says that all ladies ain't the same.

The basis is that it seems I've forgotten how to fall in love or show affection; no matter how hard I try, the brick wall built around my heart just keeps bouncing off any emotional feelings that tried to breakthrough, so this is why I decided to ask those who are in it or have once experienced heartbreak at one point in life or another to guide me on how they overcame the experience and how they were able to move on from it.

Thanks for reading, I look forward to your response in the comments section, have a blessed day.