First things first: his insecurity is his, not yours. You can be as supportive and awesome as you are clearly already being, but this is still his thing to work through, because you’ve done everything you can. There’s no magical thing you can say that will
make him understand that you’re okay with waiting. Please don’t feel guilty. Don’t take on that added burden, because it may read to him as upset from a different source—like, say, sexual frustration. From what you’ve said here, you’ve been straight with him, you’ve used your words, and if he doesn’t believe you, that falls squarely under His Problem.
However, obviously you want him to be happy and comfortable and not worried that you’re going to leave him. So.
Part of the problem here might be that he’s suddenly got this Specific Date by which he feels he
has to be ready, and if he’s not ready, he’ll be letting you down. But hanging out with him is not a letdown! He makes you happy! It is great to be with him no matter what you are doing! So, keep your V-Day plans—in that if the hotel is already booked and you can’t/don’t want to cancel it, I’d advise going anyway and spending the night (or whatever) as planned. What you can maybe do, though, is dial back the expectations so that sex is not The Reason You Are Here; when you guys walk in there, it is with the understanding that pants/skirts are staying on and buttoned and done up. Hang out. Cuddle. Make out like teenagers. Whatever makes you guys happy. You don't need sex to have a good time, as you both clearly already know after several months together; you are still cuddling and making out and mocking bad TV shows and talking about shared interests and having awesome fun sexy-without-PIV-sex hangout times together in a fancy room that you do not have to clean. And it will be great.
Once V-day has passed and that social pressure is off both of you, maybe sit him down to talk about it. Not about sex—if he’s not ready, he’s not ready, and that’s that, and you’re fine with that, and you’re sure he’ll update you when the situation changes. But it’s a good opening for the thing that you sound really concerned about: that he doesn’t believe that you’re willing to be patient. Maybe ask about that. Express that you love him, express that that’s way more important to you than sex (as it sounds like it is), express that being with him makes you happy, and express that you want him to trust you. Then listen to what he has to say.
Personally, I would strongly advise against just shutting the topic down and waiting for him to bring it up first, mostly because he was the one to put the brakes on and he might be horribly embarrassed to bring it up again, especially if he feels like he is disappointing you. Having some experience with shy awkward virgin boys (and having been a shy awkward virgin myself), there is this feeling of
if s/he doesn’t talk about it again it’s because I’ve ******** everything up and now s/he hates me and oh god what have I done let’s just never talk about it ever and maybe it’ll go away. And then I’d never bring it up again for fear that if I did, I was reminding the other person that they had a reason to be disappointed in me.
So! That is Silent’s Advice Corner. If you want advice from someone way smarter than me, though, might I recommend
Captain Awkward, the advice blog? She’s really awesome about stuff like sex, using words, having the awkward discussions, and so on and so forth. You might even find something in the archives without having to send in a question of your own!