Why?

Why do people feel like its okay to lie to me? The guy I was dealing with lied to me about being in a relationship with this other girl. Then another guy I talk to online probably doesn't even know that I know, but I know he's in a relationship too. And he has yet to tell me, which I consider a lie. And today, my very own mother.... The woman who birthed me, lied to me about who she was with... Am I just a easy target to tell lies to or something? Do I look that dumb or naive? But just like I told my mother, I see and know a whole lot more than I'm given credit for... And just because I don't say anything about it, doesn't mean I don't know about it.