Not sure if everyone would really consider this an "et tu, Brute?" moment, and it's quite petty in relation to a lot of the other responses, but I have some time so figured I might as well share anyway.
Oh, and I guess I should preface this with the fact I've never been in a relationship before. I'm bad at picking up on signals and I'm bad at starting something with someone I'm interested in.
I started college this past summer. I didn't know anyone, and at orientation I was immediately smitten by a quiet girl who also didn't know anyone. I talked to her a little at orientation, but that was it.
The next day, I was early for my first class, so I was exploring the school a little bit. I was browsing the book store when she walked in. We exchanged a smile and that was it.
I went to class and sat down near the back (small college, small classes - basically high school size classrooms). Lucky for me, cute girl from earlier has the same class. She walks in, sees me, smiles, and sits beside me. We talk the entire class, and near the end she hands me a piece of paper with her number on it. Score!
We talk constantly and get to know each other, and classes with her are tons of fun. I'm obsessed with this girl even though she isn't anything like what I would've said my dream girl was if you asked me. And for once in my life, it seems like she's as into me as I am into her.
Then, in passing, she mentions something her boyfriend did as if she talks about him every day. Waitwaitwait, boyfriend? Well, shit. That really sucks. Oh well, I still really like spending time with this girl, so I guess friends is fine.
Fast forward to last month, we're still really close, and I try and ask about her boyfriend every so often just to be a nice friend (honestly). She complained about stuff he was doing fairly regularly, but out of nowhere she would change the subject if I ever tried to ask about him. She'd ignore his texts when she was with me too. I assumed things weren't going perfectly, so I wasn't persistent but I did try to let her know that she could talk to me if she needed (if she ever considered dating me before, that probably stopped at this point).
She never told me if they broke up (or even if they were fighting or anything like that), but she did constantly tell me she wanted to hang out a bunch during the break. I was looking forward to it, then break came and went without her answering a single message about hanging out.
The new term starts, and she starts telling me about her new boyfriend. Who she asked out.
I'm still close with her, and I still have a huge crush on her, but it's always frustrating when she calls me upset because of something her boyfriend did. The last time she was sick, I was the one who drove an hour out to bring her lunch, not her boyfriend. I need to get over her.
The real kicker is that I've actually had a couple girls express interest in me since I met this girl, but I'm just not interested. This beautiful waitress asked me out to coffee, and she was great, but even after coffee I just wasn't interested.
Wow, sorry, that was long and it probably isn't even an "et tu, Brute?" moment. I just kinda took the opportunity to type out my frustrations.