Unsure?

I have recently discovered that a few guys that used to talk to me quite frequently don't talk to me as much (if at all) any more. Not to sound conceited or anything but I came up with the theory that they either had feelings for me or got tired of talking to me. I usually would lean towards the latter but why did it stop so abruptly? Thus, I have come to the conclusion that if you want to know if someone is interested in you, get into a relationship with someone else and see if they stop talking to you. If they do, chances are, they had feelings for you.. Or at least, that only seems like the plausible explanation.. but then again, maybe they just found something better.