Thank you for raising your questions to the Wefugee Community!
Your friend's situation is still not very clear to me. As far as I understood, he is an asylum seeker in Italy? If this is the case, he will not be allowed to travel to Germany or to leave Italy as long as the asylum procedure is still pending.
However, if he can provide all required documents, they might want to marry in Italy (please find discussions we had on this earlier, for example, here)?
If your friend is able to get a residence permit in Germany related to his German (then) wife, there would be no need to apply for asylum anymore.
Please get back to us if any clarification is needed or if you want to discuss your friend's case further.
All the best,