Was I Insecure Here?

Something's been on my mind for quite a while, and I want to know: Is it okay for someone who you're seeing to be messaging another friend of yours as much as he does to you or more even though there's nothing sexual?

P.S.:: I didn't stop talking to him because of her, it's because of a whole other reason not related to my friend! Just FYI~

In short, a close friend of mine and a guy I liked would always message each other whenever we weren't talking (in a friendly manner, I saw convos they had w/ each other and I know my friend. She knows her boundaries yet, I've realized, she doesn't recognize what's wrong at questionable times). I used to bring it up with her several times but she'd give me this blank expression like she was confused. Another friend of mine called me "insecure" because I said I was uncomfortable with what was going on, it was strange to me. I hate to admit, but I also did make my friend cry because after a few months, I got fed up and indirectly lashed at her (ex. stopped talking to her).

I remember not being loud enough when telling her I didn't like this situation. Ugh, I wish I had more confidence then. I just didn't know, I've never been in a real relationship and that was my first, so was I supposed to let it slide?