I think with all the emotional trouble he's carrying, and that this is really something quite new, and happening quite fast, it's perfectly reasonable for him to refuse fucking just yet. That's an incredible amount of vulnerability there, and just loving someone isn't enough to get over worry and nervousness of such a thing. If he's not ready, he's not ready - and I think I can see that Draco understands that. When it's time, they'll know. It's not all about penetration anyhow ;)