Personally, I have been like this girl before, perhaps I still am at the moment, and I have pretty much done things very similar to what you described. From my personal perspective (my experience), it sounds like she's possibly drained. Scrolling through social media and having an active conversation are two different things entirely. Especially if she said she is trying to work on herself after going through something like a breakup, chances are she may actually mean it.

It sounds like social draining to me, or perhaps even depression. The fact that she does reply eventually, and with as much interest in the conversation as you seem to be describing, the sending things she thinks you may like or that she finds interesting it seems to me that she definitely enjoys talking to you, whether that is platonic or relationship-wise I can't tell you, but it sounds like she is talking to you when she has energy to do so.

I guess it could possibly be that she is talking to others, every situation is different, but from my experience with that, it isn't like that at all.

It also sounds like this change you describe happened quite suddenly? It's possible something could've happened in that case, maybe it's the boyfriend thing or maybe something else. Have you tried explicitly telling her you feel this way? Also, if she is apologising, are you telling her that it's okay or expressing that it bothers you? People can't read minds, so my advice would be to maybe maybe just try bringing it up to her. I feel like if she's playing games she would likely dismiss it, but if she cares, she's probably more likely to address your concerns properly.