My (19M) girlfriend (19F) have been having sexual interactions for 4 years now. One issue that has been and remains a problem, is that once she orgasms, she completely loses the mood. She is still willing to please me afterwards, but it is lazy and she is very obviously physically tired. We have talked about working towards us orgasming together, but other than that, we are unsure where to go. Is there any advice someone could provide? Potentially a way to keep her in the mood after an orgasm.