to + inf vs to + '-ing'

Question

I have been doing an online test to check my English skills and found this:

I was looking forward ____ at the new restaurant, but it was closed.

Incorrect (your answer):
to eat

Correct:
to eating

I had understood that after 'to' comes the infinitive form. Could anyone please explain why I am wrong in this case?

Answer 1

“Looking forward to eating” is correct here.

“Looking forward to” is acting like a phrasal verb that wants a direct object — a noun.

I am looking forward to the test

She is looking forward to the new “Star Wars” movie.

They are looking forward to a better future.

We are looking forward to running a marathon.

I was looking forward to eating at the restaurant.

You’re right that “to” usually takes an infinitive verb.

I want to run a marathon.

Some verbs can take either a noun, a gerund, or an infinitive verb as their “object”.

I hate to run.

I hate the test.

I hate running.

Many very simple (usually 4-letter) verbs work this way:

• I want to swim,
• I love to swim,
• I like to swim,
• I plan to swim,
• I need to swim,
• I intend to swim

while other verbs do not:

• No: I enjoy to swim.

Unfortunately, “look forward to” is a verb that doesn’t work this way. It requires only a noun or a gerund.

Yes: I look forward to running (the race).

Yes: I look forward to the race.

No: I look forward to run the race.

Answer 2

"Looking forward to(something)" is a phrasal verb, meaning that you treat the phrase as you would a verb. Therefore, the something in question can only be either a 1.+ing verb or 2.a noun

So, to eat+ing is the correct answer.