Like everyone else is saying this absolutely could turn out to be trash, really depends what direction the author goes. Personally, since Lemon is clearly the main heroine, i wouldn't invest too much into the other girl. She might have a legit reason to have dumped him or whatever and she clearly regrets doing that to him, so maybe it can be resolved some way. I hope they focus on Lemon as a character and make her interesting. But i know that the incels will cry about her dumping him in the first place, because anything other than a "totally realistic" love at first sight and stay together for the rest of your lives without any doubt in the relationship is unacceptable. To the guys who will never find love.
But i could also be wrong and this can turn out to be a dumpster fire like Domestic na Kanojo or Kanojo Okarishimasu.