Hah, these battles are hard. Or maybe I'm missing something?
There are basically two ways to lose, right? By losing the tug-of-war bar at the top, and by losing all your hearts? This part seemed pretty clear, though it felt like the battles generally boiled down to hearts in the end.
The stars were a bit less clear—they're supposed to add power to your actions, right? Does the effect of stars vary per person? (I feel like I stuffed a bunch of stars into the blonde lady, but realized too late that all of her actions still just showed one star of impact). It took a few rounds before I properly noticed that different people had different stats, and were taking turns—at first it just seemed like the impact of the stars was fluctuating unpredictably. (In retrospect, I think maybe the initial tutorial tried to say something about this, but I lost that battle and the game just moved on so maybe all the data there didn't make it into longer-term memory.)
After starting to understand the rules (I think), I had some trouble following everything—things happen pretty fast and in different sections of the screen, while at the same time I as a new player was trying to look at and learn all the pieces enough to figure out some strategy without getting distracted by how my band is getting pummeled. Some extra animation and redundant visual cues might help here, e.g. by shining a spotlight on the currently-active member, by tinting the screen (or just overlay a low opacity-color) a bit when getting hit/blocking, or by making the band's bar glow their color (e.g. have a color with an alpha gradient scale out) when hyping the crowd.
On the whole, though, the battles also just seem hard—the odds start stacked against the player (with the opponents having more health), clicking each individual star has to be done quickly so the opponent doesn't get multiple actions off in the meantime, and battles start after reading / clicking around for a few minutes (with the mental mode-shift feeling like it starts me off on the wrong foot, and making it hard to get into a flow state). If you'd like to make the VN the focus over the battles, I would definitely suggest toning the difficulty down by default, if only by reducing the rate that opponents act.
Sorry, I hope this doesn't come off too critical—from the description it sounded like you're looking for all feedback, particularly on the battles, and I definitely struggled with those.
On to the good stuff:
I like the animations during the battles and found the plot pretty engaging.
The text-changing was a nice touch—I customized every name, but the ex-boyfriend's text still worked out perfectly, as far as I noticed. I'm curious to look at the code there and see how that was done.
I'm impressed by all the work put in here. Wish the difficulty ramped up more gradually so I could see more.
Good luck developing this further!