What exactly am I feeling?

So there's this guy, he's like my best friend and I think he's sweet, kind and totally great kind of guy even when not my periods (but i don't feel the want to talk to him 24/7) but everytime I'm on my periods I fall for him as if I'm obsessed. If i don't feel anything for him, i start feeling it and if I'm already feeling it, it's totally heightened up. It is never any other guy that I'm attracted to during those 5 days and this is happening since past one year. What does this mean? Do i actually like him? Is he controlling my sex hormones? Is this a type of disorder to feel it for the same person everytime cause i can't live 40 more years of feeling things for him this way! So what is it?

What exactly am I feeling?
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