Why a different verb form here
Someone who wants, hopes or feels is not reporting the event in the subordinate clause as a neutral fact, but as something wished for or evaluated. Spanish marks that on the verb: after que comes the subjuntivo.
The biggest trap: “I want you to…”
English has two ways to express a wish. Same person: I want to go. Different people: I want you to go, again with an infinitive, just with an object in front of it.
Spanish copies the first pattern and refuses the second. There is no Spanish sentence shaped like want + person + to + verb. Same subject in both halves → infinitive, no que. Different subjects → que + subjuntivo.
What has to happen to the English sentence
One subject vs. two subjects
Same subject → infinitive
Quiero ir a España.
I want to go to Spain. (I want = I go)
Espero llegar a tiempo.
I hope to arrive on time. (I hope = I arrive)
Different subjects → que + subjuntivo
Quiero que vayas a España.
I want you to go to Spain. (I ≠ you)
Espero que llegues a tiempo.
I hope you arrive on time. (I ≠ you)
Verbs of wanting
Typical wish verbs
querer que
to want someone to
desear que
to wish that
esperar que
to hope that
preferir que
to prefer that someone
pedir que
to ask someone to
necesitar que
to need someone to
Wishes in full sentences
Espero que todo salga bien.
I hope everything goes well.
Te pido que me ayudes.
I'm asking you to help me.
Mis padres quieren que estudie medicina.
My parents want me to study medicine.
These wishes all point forward in time, yet none uses a future tense. The present subjuntivo covers now and later alike: I hope he will come is Espero que venga.
Verbs of feeling
Reactions (joy, regret, irritation, worry) behave exactly like wishes: after que the verb goes into the subjuntivo. Most of these expressions work like gustar: the thing that causes the feeling is the grammatical subject, and the person who feels it is an object pronoun (me, te, le …). Me molesta que… is literally it annoys me that…. With the same subject you use the infinitive here too: Me alegra estar aquí. (I'm glad to be here.)
Typical expressions of feeling
me alegra que
I'm glad that
me encanta que
I love that
me gusta que
I like that
siento que
I'm sorry that
me molesta que
it annoys me that
me preocupa que
it worries me that
With alegrarse, de goes before que: Me alegro de que estés aquí.
Feelings in full sentences
Me alegra que estés aquí.
I'm glad you're here.
Me encanta que cocines así.
I love that you cook like this.
Siento que no puedas venir.
I'm sorry you can't come.
Me preocupa que no duermas bien.
It worries me that you don't sleep well.
