I lent a few books to this girl I know, who I've seen a few times before, before the break, and a few weeks later she texted me out of the blue saying she had been reading and was looking forward to many interesting discussions. I go into her place of work often (not ideal, I know, to make myself so available, but it's a great hangout spot where I know a ton of people) and ran into her there the other day now that she's back in town. We agreed to meet a couple of days later, but it got cut short for reasons out of our control and we only got to talk for thirty minutes or so, so we set up again two days after that at a specific place and time. I text her confirming the night before, and she texts me the next day around noon (two hours prior) saying she was busy and sorry she wouldn't be able to meet today. Fine, it happens, could've let me know sooner, but she could have suggested another time. In good form, I did not respond to the text and have not seen her since then, a few days ago.

I recently saw this post and composed a text (but did not send) along the lines of "Sounds like you aren't interested in meeting again or would've suggested another time. See you around." If you read the post, the idea is to 1) not put up with ambiguity 2) set clear boundaries for what you're willing to put up with from a girl 3) make her realize that your attention is a valuable thing and not given freely. The problem is, wouldn't this come off as clingy? Is there a way to say the same thing in a more assertive way? The conflict is between seeming like I don't give a fuck (which is a lie) and not being a total pushover. I'm getting better at it, and I've confronted this girl about her lack of respect in a particular conversation we had once, and I felt GREAT after we both agreed eye to eye that she was being disrespectful. I want to train myself to be more assertive (No More Mr. Nice Guy) but don't want to seem moody and irritable and sensitive. Thoughts? What is the middle path like?