Why didn't my boyfriend let me see the hotel front desk when he took me to check in?

There are many possibilities. I'll make a list for you. See which is more like:

1 He doesn't want you to register together, because you need to register your ID card information to open a room;

He is thin-skinned and embarrassed.

Have acquaintances or don't want others to see them.

There are many more, so I won't list them one by one. All I can say is, do you know him? It's not a good thing to cool you down anyway. You'd better pay attention. Do you know him at school? Learn more.