What are the reasons why boys are scared by girls?

It means that your boyfriend wanted to surprise you, so he didn't tell you in advance that he would come to you. He just wants to pop up in front of you. He wanted to surprise you, not scare you. He just wants to be with you, just wants to talk to you.

So you don't have to be too scared, because after all, he is your boyfriend, and he will definitely not hurt you. He just wants to please you.