I think I am going to have to breakup with the perfect man

I (23F) am with my partner (26M), for almost 4years now, and this man is the love my life. He is the perfect guy, and if there is some problem on his end, he constantly acknowledges the problem and improves himself. I am a person who likes to communicate about everything, and he is the type to listen, pay attention and work alongside with me on the relationship to make it work. We have had many problems, ngl, but we have overcome all of those.

But there is a key factor that is missing (which I will not be specifying). And it is a big thing. We have had conversations about it many a times but it just doesn't seem to change, at all. For the past 4years, I have been holding on to the hope that it'll change. We talk, he says that he is going to change, but it remains the same, and I'm here sitting with the expectation that it'll work out.

But I don't think it is gonna. I think I have finally realised that he probably doesn't have a control over that, because trust me when I say this, that man will do anything to make me happy. But this one thing, this one gosh darn thing, is missing from this "perfect relationship". And I feel like if I address it again with the new realisation, the TALK will proceed to us just breaking up. Because I don't see any other way.

I have seen my future with this man, I love him to the moon and back. He is so intricately involved in my life and I, in his. I have been having such a difficult time. Every other moment I am having a breakdown thinking about a life without him in it. We can't spend a day without talking to each other, but I'm avoiding him like crazy. Because Ik if we speak, I'll blurt out of just initiate the talk, and it'll escalate.

He has his career pivoting moment coming up in like 2 months or so, and I don't want to take away his focus from his career and destroy it. I feel like I'm suffocating, i don't know what to do. I can't proceed without having the talk, l cannot have the talk without destroying his career, i cannot keep mourning the relationship even before it is over, I don't want it to be over. I can't keep on avoiding him for 2months, obviously.

I just don't know how to deal with this situation. How do you deal with such a scenario? How long should I keep this within me?

TL;DR- I think I might have to break up with the man of my dreams for one major point (won't specify), because finally realised that even after having in numerous talks about this matter, it has not changed in 4years (probably because it is out of his control as well). He has a very important career moment coming in 2months and I do not want to ruin his focus, henceforth his career by having this talk, which might ultimately lead up to us breaking up. I don't want to break up but it seems like the last string. Idk what to do. How do I deal with this situation?