Learn Spanish (Latin America): Nos decepciona que ellos no te ayuden. - It disappoints us that they don't help you.

When you express a feeling or emotion about someone else's action, you use the subjunctive. Here, nos decepciona (it disappoints us) expresses the emotion, the word que connects the ideas, and the subject changes to ellos (they). Because of this combination, the second verb must be in the subjunctive: ayuden.

Why is it Nos decepciona instead of Nosotros decepcionamos?

Decepcionar works just like the verb gustar. The literal translation is closer to "It is disappointing to us." The entire second half of the sentence (that they don't help you) is the actual subject causing the emotion, so the verb is conjugated in the singular "it" form (decepciona). Nos simply tells us who is receiving that disappointment.

Why is the pronoun te before ayuden rather than attached to it?

With a normal conjugated verb like ayuden, object pronouns like te must go directly before the verb. You can only attach pronouns to the end of infinitives (like ayudarte), gerunds (like ayudándote), or affirmative commands.

Could we drop the word ellos from this sentence?