In novels where the main character breaks up with the love interest because THEY think that's what is best for the love interest. I mean it's not that bad because everyone have the right to self preservation but is it really for the love interest? Or it's really what is best for themselves because they find it hard to see their partner struggle and doesn't want to be part of that? I see that in reality a lot, I guess it's fine because they didn't promise to be together in sickness and in health which in our reality doesn't really get fulfilled much, mc probably sign up just for the happy part, and often ml would be there for the mc through the most tragic happening but then the mc will not reciprocate and think that abandoning someone who loves them their whole life is the best solution to that problem. But it's like if I didn't sign up to read a story about a person like mc, if I do I'd just listen to my friend's or neighbors story which is much more immersive. I just find it hypocrite for the mc to be written as a selfless angel who thinks he loves the ml unconditionally even when they're far away, I mean what can that do? While you're on the company of another side love interest getting their attention. I as much as possible avoid novels like this can't be avoided, unlike when I read in ridi.
I don't remember ever reading a novel where this happened, tbh, but... Well, it's just a weird thing to be done, I guess? I mean, if I'm dating someone, it's because I really like this person and want to be this person... If this person is struggling, then I want to be there to support them and help them when they need. I can't imagine breaking up because I think it would be better for them... Like, what? Why would breaking up with me would be better for you when I love you and am doing everything I can to support you? How does that make any sense? If I were to break up with someone, it would be because that's better for me. Because I'm the one being hurt by the relationship. Because I can't handle the way things are going anymore... It just doesn't sound right to break up with someone for their sake, like... What? Unless it was like... I dunno, a random dumb supervillain scenario, "If you don't break up with this guy, I'll kill him!" Then yeah, sure, I'll break up with him. Please don't kill him. ... Otherwise, it just feels weird.
Right, that would be understandable if it was like that! That author probably have never been in love.
The reason for this kind of story line is that the author created a really awesome love interest and feels the need for the protagonist to do something to be worthy of him. In this case, this something is the amount that she is willing to sacrifice on his behalf. This kind of sacrifice is doubly useful because it also creates some extra drama in the relationship without actually threatening anything. You can see how popular this plot is by looking at how many TV serials will introduce a "must go away and be separated from my love interest" story somewhere near the end of the show.