It’s not so funny how you think that what you and another person have is solid but, it turns out to be quite fragile. What’s really going on here I asked myself (and God) until I received an answer. Make it make sense. The simple answer is you may have been way more invested in it, the friendship, relationship, partnership than they were. It may have been layered with somewhat equal exchanges but the EMOTIONAL investment for you was much greater. Therefore, you feel a bigger let down and may have difficulty “wrapping your head around” their ability to move on as if it was nothing. I’m not saying they didn’t care. I am saying it was just not as much as you did. The bond was only on your end and your “deep” connection was more than likely a one way thing.