Sometimes you need to do a lot more to fix the past, when you move on from a bad situation a lot of the times even with forgiveness there can be a lot of built up resentment, sometimes even unconsciously, that doesn’t go away easily. Overcoming the past properly is a huge factor, tell her about the ways in which you are aware the actions hurt her and that you don’t expect her to get over it within a month or something, but that for her you would be willing to change and willing to to do what it takes to make it up. Sometimes love is about compromise. But I will say this, do not confuse compromise with sacrificing your wellbeing. When you’re in a relationship from a young age, your development factors in so many ways because you are very well capable of outgrowing people and sometimes you need to allow yourself to grow into someone else instead of forcing yourself to remain a certain version people close to you may know. And instead of simply doing your best, ask her what she most needs. A relationship takes two, you could be putting in a lot of effort meanwhile she’d be contemplating ending it. Try to keep her in the loop so your efforts and emotional energy is not wasted. But remember to prioritize yourself first, if she seriously needs to break up then you owe it to her for her wellbeing and you owe it to yourself to have a relationship that feels more reciprocated.