Being able to say yes is important. Being able to say no is important.
Being able to say maybe is also important.
It’s usually ok not to know what you want, even if others want you to decide right away. You don’t always have to know reasons. It’s ok to just feel unsure. Feeling uncertain is an ok reason not to say yes right away.
Sometimes there’s legitimate time pressure and people do need you to make a decision right away. It’s ok to say no if you’re not sure.
And when there isn’t time pressure, it’s ok to say maybe. Even if that annoys others.