Do you guys have this too?

I often seem to be in a situation where a girl is giving all the signs she's into me, but then she says she's not. Like, all my friends would think they are into me, or I would watch those 10 SIGNS SHE LIKES YOU videos and all the signs would match. It's probably something I do or the way I act that makes those girls feel really comfortable or something but they never like me in the way I like them though it seems they really do. I was wondering if any of you have had the same problems and maybe have some tips to overcome this. I want to stay myself of course, but I feel like there's always this little thing that just gets in the way of them liking me as more than a (good) friend but I just don't know what it is.