I’m a female member.

I’m Joe, the column writer. I agree. That said, when I really like someone, I tend to invite her on a trip fairly early on. As you mentioned, there can be a strong sense of resistance to sleeping together or letting someone see you without makeup. I’m embarrassed to admit that I used to be unaware that many women feel this way. This is just my guess, but I feel that many men either don’t realize how important this is or simply don’t know. So, as Leaf-san has already pointed out, if you’re invited again, it might be best to say something like, “I’m still embarrassed about you seeing me without makeup,” or “I’m not quite comfortable sleeping in the same room yet.”