I just want to share my most recent experience.

There was this chick at my work that started to get closer to me, very talkative and friendly. The time past and at the end she ended up telling me her interest in me, telling me that I was the cutest guy in the floor, that I was the only guy different from the others so I was her only interest,etc, etc. Since this was at work (you don't shit where you eat) I just tell her that I wasn't insterested but that we can continue as friends (I just didn't want to make drama so I just told her that). She accept it miraculously well and calm, which surprised me.

After that she just confessed me that I was only the first option out of 3. She then proceeds to start talking with her other option. This other guy gave her attention and curently they are dating. All of this happened in less than 2 weeks.

Beware when women tells you that you are the only one, this is NEVER ever the thruth. They hold a list of guys in their backs at all times.