Maybe because they bring someone else around their friends. Maybe because they don't want people to know about you. Maybe because they're not sure of you. Every reason boils down to the same thing: what they want from you is the option of a plan B.
You text more than you actually do things
Pen pals were great in second grade. And though consistent texts and phone calls might feel intimate, they're not there to replace actual intimacy. "William" did this to me for quite a long time, combining a manufactured, distant closeness with making plans and never following through.
You know why? Because he also had a girlfriend. And he liked keeping me around and available for the attention I gave him, the security that I'd be there if things with his girlfriend didn't work out, and the ego trip of having more than one person infatuated with you.
Yeah. What a stud.
They actually tell you
Yeah, this seems pretty obvious. But I've lost count of how many people (myself included) who, even in the face of the truth, spin things in our favor.
I had a crush on a guy once who we'll call Alex. The whole flirtatious thing was upon us, and we ended up going out a few times. Then he told me about another girl, let’s call her Jasmine, and that she was "finally single after all this time." Except instead of bailing right then, I kept seeing him. Even though he pursued Jasmine... and began dating her. Several weeks (OK, years) of him continuing to play games -- because he cheated on her a lot -- I eventually jumped ship and moved to Southeast Asia. Because sometimes you have to make big changes to move on from big heartbreak.