Früher begriff ich nicht, warum ich auf meine Frage keine Antwort bekam, heute begreife ich nicht, wie ich glauben konnte, fragen zu können. Aber ich glaubte ja gar nicht, ich fragte nur.
Previously I did not understand why I got no answer to my question; today I do not understand how I could believe I was capable of asking. But I didn't really believe, I only asked. [Kaiser/Wilkins]
Earlier, I didn't understand why I got no answer to my question, today I don't understand how I presumed to ask a question. But then I didn't presume, I only asked. [Hofmann]
Both this and the previous aphorisms must have something to do with Felice Bauer. How stupid of me not to notice earlier! On the other hand, these are gathered together among a set of numbered aphorisms, which suggests to me that there is a generalizable kernel in these passages. Kafka does not seem to want to answer a question of this magnitude using only this or that part of his being, but with his whole being, which includes his unparalleled ratiocinative power.
In number thirty-five, he must be speaking of Felice when he speaking of a Being. Marriage is not about "having a spouse," it is the presence of a being whose existence is fundamentally merged with your own. In that case, perhaps the desire for the last breath might be hers, and the aphorism would express his fear of destroying her in a marriage. Or that last breath, the Being, might be Kafka after all, anticipating his own destruction in marriage.
The Kaiser/Wilkins translation is more strictly literal. Hofmann conflates being able to ask with presumption, which is not necessarily the same thing. As far as a marriage proposal is concerned, it does however seem to be the same.
What matters, though, is the difference over time. Back then, it was the lack of an answer that I didn't understand, now it's my own asking that I don't understand. Kafka returns to the difficulty that arises when you try to relate two points of view. Kierkegaard, whom Kafka read, came back again and again to the idea that having a point of view entails having a blind spot. The presumption is an interpretation after the fact, not the motive.