What are you? A person or just a doormat? Show a little bit of pride, here.
Clue time. If you don't want to do something, just don't bloody well do it. You need no ones permission to say no - not in the first week of a relationship, not in the 30th year of a relationship.
You realise that the whole boyfriend/girlfriend thing is actually a partnership, right? And that both partners have an equal say? And if he wants you to do something you don't want to, or like, or are simply not in the mood for that evening, then it is your right, and his tough luck if you say no.
His eyes don't matter here. What matters is you being comfortable in your relationship.
That is all.
And after that, if he tries to "talk you into it"... run.