How can I make sure that I really know the guy I like?

Lauren writes, "What does it mean when a guy you thought you knew real well (thinking he was a genuine person), was pretty sure he really liked you (and then started to like him back), and you knew for over a year and a half, that you have feelings for him, and his response is: "Well first of all, you don't know me at all. You do not know me well enough to say that and that if you knew me for who I really was, I know you would not be saying or feeling that at all." And then tells you that he still wants to keep in touch, does not want anything to change because it's not a big deal and still hopes we can be "cool" about everything?"

I think what this person is saying that he is not what you think. For instance, in an extreme case, he may not even be single, but most likely, he may not be from the social class that you think he is from, or have the education/job/income that you think he does, or have other secrets that you may not know.

It does not mean that he told you any lies; a lot of time we just don't know enough about people even after a long time, though, no one told any lies. For example, I might meet a woman who constantly talks about wines and I might conclude that she must be a fine woman to have such a serious passion for wines, but she could be just a college dropout with a simple job in the mall but has simply indulged her passion for wines for years. She might make little money, live in a humble place, be a great person but if I start to allude to her high-class status, she can correct me by saying that I don't know enough about her.

I think this man has essentially told you that he is not interested in a romantic relationship with you but appreciates your acquaintance or friendship.