Decide

as in

"You never decide anything."

Variations: "You never make up your mind ... never say what you want ... never tell me what you are thinking.."

Obviously we are into the realm of exaggeration here. Even the most laissez-faire of boys must decide some things from time to time. In fact, it’s a fact that they do. Like when they want another drink. When they want to sleep for an extra hour. When they don’t want to be bothered getting up to put out the trash. No problems with decision making there. These are all cases when men frequently show
considerable authority.

What she is referring to is a more rarefied realm of action. Serious matters. Usually with a strong romantic connotation.

Like ... deciding that you want to go out with her, and only her, forever.... that the two of you are going to get married... going to buy a house... going to have children.

These are the areas where she is liable to notice you find it hard coming up with a solid final decisive answer.

Clearly - given that these are very tough questions deserving, you’ll agree, the greatest possible respect - she is being a little over optimistic to think you would have an answer yet. You need time.

Still it may be best to humour her. Assure her you will get on the case immediately. With any luck, something will happen to divert her, perhaps the country will go to war or Martians land.