<human>: Genders and ages aren't important, because I'm sure this situation isn't uncommon. In this case, I'm F, the other person is M. Shame they are necessary in the title...

I have a hunch that M may be interested in dating me; he's invited me for walks (to somewhat special places) etc. I don't mind him as a distant friend / acquaintance, and would help him out if he was in big trouble, but I'm actively keen on spending time with him.

I organised a party, he was not invited on purpose. I didn't want him there. Now he's expressing regret about missing it and stating that he needs to join the mailing list to be in the loop next time.

How do I diplomatically tell him that while I don't dislike him, I'm not super keen on his company, especially when the parties are for close friends only.

I'm guessing many of the anwers will be "just tell him" but is there a way of being diplomatic about it, without being a dick?

Summarize the given text in a few sentences.
<bot>: I, on purpose, didn't invite an acquaintance to my party, they now express regret about missing it. How do I tell them the truth (to get them to stop trying)?