It doesn't sound that vague to me. It seems like she wants him to improve his daily communication, this can be just being open to talking about his day, plans for the upcoming week ect..If he isn't doing that about himself it seems like he's also not that easy to open up to even about little things like her day. It's also infuriating if you ask your partner questions like what do you want for dinner, what would you like to watch tonight? And they constantly say they don't know or care, putting the onus completely on her to plan things.

Then when she does, it sounds like he doesn't communicate that he sees and appreciates what she does. If he can't handle daily conversation then he absolutely can't handle serious ones which is where her breakup comment came from. Imagine telling your partner you're thinking of breaking up and he doesn't say anything of value to help the issues. How can you move forward when you know any tough talks result in a one sided conversation. This wouldn't fly with me, you deserve an equal partner and he's absolutely not being that.