So let's say, that you've been getting closer to a guy for the last five months and you reached a point where you'd hang out together alone and text everyday for hours, and you'd both told the other you like them, and did sweet things like texting good luck before the GRE and every single night of a play's run and before a band's show and what not. So all of that has happened and then you see each other this past Monday, at his request, you have a good time, and then he stops talking to you. When you text him, he texts back, but the responses are short and there's never a conversation.
So this whole time you've only been friends, but now you're confused, you don't know what happened, and seeing his stupid face now makes you sad. Would you ask for an explanation or just let it go?
Clearly this isn't hypothetical, it was just easier to type it like it was.
Edit- Thanks for the advice everyone! I texted him (in a round about, non-accusatory sort of way) and he apologized; he didn't realize how little we'd talked this week until I said something and we made plans for this week. Happy ending!