What to do in this crappy situation?

I was in a LDR when i started feeling bored, I chatted with a guy (without any bad intention) but I dontknow I never felt the feeling I feel for this guy for anyone, I never told him. I think he started to like me too but never said. So basically we do talk once in a while but never said anything to each other. In the meanwhile my LDR ended but the feelings never fade away for this guy. He wanted to meet me i denied because I as already in a relationship with whom I was gonna get married. But again, the feelings doesn't go away. Also, I love my boyfriend a lot, and I can't even imagine leaving him. But sometimes out of the blue i miss the other guy, i actually yearn for him, i do not even know why? Can you all help why i do feel this way? And what shall i do?

What to do in this crappy situation?
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