Breakdown of Der Pony ist schief. Ich hätte aufhören müssen.
ich
I
sein
to be
haben
to have
müssen
to have to, must
Questions & Answers about Der Pony ist schief. Ich hätte aufhören müssen.
Wait, "Pony"? Doesn't that mean a small horse?
It can! But in German, der Pony also means "bangs" or a "fringe" (the haircut). Fun fact: when talking about the haircut, it is a masculine noun (der Pony), but the small horse is neuter (das Pony).
Why is hätte used here instead of habe?
This uses the Konjunktiv II (Subjunctive II) to express a past regret. If you said Ich habe aufhören müssen, it would mean "I had to stop" as a simple fact. By changing habe to hätte, it becomes hypothetical: "I would have had to stop" (meaning you didn't stop, and now your bangs are crooked!).
Why are there two infinitives at the end (aufhören müssen) instead of a past participle like gemusst?
This is the "double infinitive" rule. In perfect tenses, when a modal verb like müssen is paired with another verb (aufhören), you drop the past participle of the modal verb. Instead, you just put both verbs in their infinitive form at the end of the sentence.
The translation says "I should have stopped". Shouldn't that be Ich hätte aufhören sollen?
Spot on! Ich hätte aufhören sollen is the literal translation of "I should have stopped." Using müssen here instead of sollen makes the regret much stronger: literally, "I would have had to stop" or "It was absolutely necessary that I stop." In English, we usually just say "I really should have stopped," which is why the translation simplifies it.