He may have an issue with his title, I highly doubt he would back out his commitment in supporting his aging wife over it. It seems like his health is the factor in this. It's better to listen to ones body than to push it just to satisfy everybody else. I don't even follow the Danish royals that much to see he's not at his best health.
I cannot help but disagree here, based on the facts we know about Henrik, his views, acts as of late and behaviour in general. I have a feeling it was last years infamous decision not to partake in the Queens very public and visible birthday celebrations, allegedly due to illness, then showing up in Venice two days later, on holiday, that was the final straw. His gripe about the title might had been justified if handled less sourly, and less personally, but instead as a more principled matter. For a long time now, it has seemed to me that he simply has not enjoyed his role, or performed it very selflessly and well, towards the people and on behalf of his family.
If this was for healthreasons, the Queen would had found a discreet way to mention it in her speech. It is not. He is a mature man, but other than being quite overweight and walking with a cane, he has no known healthissues. He would also not keep his patronages etc, if he was in cognitive decline. He would not be able to keep serving their cause if he was on a predictable decline.
I am quite sure that this process is not entirely his own. His erratic behaviour lately, his sour disposition and his clear unwillingness to accept the systemic disparity of a wife becoming queen if married to a king, but not vice versa, I think finally told the Queen, the RF and quite possibly senior members of the cabinet that it might be time to allow the Prince Consort go end his public life with dignity, instead of having his entire career scarred by his inability to toe the line.
I must say, I don't quite sympathise much with a very privileged man, who has more in life than most people can or will ever have, being repetitive, tiresome and visibly uninterested in public. When he left the Queen alone last year to celebrate her birthday with the Danish people, who respect her very much, to go on holiday, I thought it became clear that his role as Consort seemed over.
The systemic injustice however, of women becoming Queen Consorts, but men being Prince Consorts, will at some point need to be properly adressed. The short statement of the Queen in her speech however, that did not explain the reasons why the Prince Consort is retiring from public life, makes it clear to me that for whatever reasons this decision was made, it was the right call.
We needn't worry about the Queen resigning though. It is not in her nature, it is not part of the Danish way of monarchy and I'm quite sure she will work even harder now, to ensure that there is no grounds for rumours in that direction in the years to come.