Well, in manga, a common way could be to have a serious face-to-face talk in a quiet place. Another option could be to send a message if it's too hard to do it in person. But it's important to be honest and clear about your intentions.
It could be that one character realizes they have grown in a different direction and gently expresses this to the other. Or, an external event could force them to see that their relationship isn't sustainable, but they handle it with maturity and kindness.
The recommendations for the invincible break-up novels were Invincible Break-up (Xiangshu), Invincible Break-up (Excellent Sesame), and Invincible Break-up (Likes Braised Hairtail). These novels could be read online on Qidian Chinese Network. Please note that these recommendations are based on the information provided by the search results. There may be other invincible break-up novels that have not been mentioned.