Provided the kissing makes you lubricated enough to take him without hurting you, I don’t see why not. And if this kissing involves touching and rubbing and general fondling, even better.
I’m really confused at why people are saying it’s absolutely not okay. Why not?
I’m assuming the OP means just kissing as opposed or oral sex or digital stimulation. Not all sex involves cunnilingus…for various reasons. And it’s not “rude” for a guy to have consensual sex with a girl without going down on her. It’s not a prerequisite of penetration.
However, like @glacial, I’m wondering what the background story of the question is, because that might change everything. Nothing should be done without the girl’s consent, of course. And if more foreplay is desired, one should ask for it. If not, it’s all about whatever you’re comfortable with.