I find that the most surprising part. In any other Royal Family I could understand it possibly but the IHA has such control and access to the Imperial Family they can't have known about this and indeed we know they did know before the actual official announcement was made so why let it go on? Nothing makes sense about it IMO - the abdication was always there. Either something has come out in the press or private that has made Mako reconsider how she sees Kei but that would have to be something major, would money really just be it?!
The IHA has a bad, controlling reputation yet they do not appear to be overly involved in Mako's relationship. I'm sure the agency would have preferred to avoid the embarrassing, unprecedented postponement.
Princess Mako, Komuro met in 2012, dated with bodyguards at distance - The Mainichi
[…]
Bodyguards from the Imperial Guard are supposed to accompany Princess Mako when she goes out. However, at the request of her parents Prince Akishino and Princess Kiko, who supported Princess Mako's relationship with Komuro, the bodyguards tried to keep a distance from the couple by blending into the crowd.
[…]
Japanese culture has strong (sometimes overwhelming) emphasis on honor, family obligation, duty, loyalty, etc. I can easily imagine a big fuss over Mrs. Komuro's money dispute.
Unfortunately her debt is Kei's debt and will become Mako's debt after marriage. I'm upset with Mrs. Komuro's ex-fiance. Since he isn't letting the matter drop, can't he be discreet?
This has me wondering, what would happen if Mako or any royal princess simply went and got married without the whole rigmarole? I know she wouldn’t get the money, but would anything else be different? I mean she loses her title and is out of the family anyway, so what difference would it make.
[...]
Huge scandal, massive shaming and dishonor. The couple would be considered immensely selfish.
I can't tell when and where the rumours came exactly as I first heard it from my friend who live in Japan (in the begin it's more like a gossip, later the local press dug deeper and deeper which makes the whole thing turned serious), but I try to give you some news and information. P.S. I don't read Japanese but I can roughly get the meaning by reading Kanji (it's similar/same with Chinese character) plus Google translation. I can't translate the whole article but I would try highlighting some key point/important part.
Source 1
眞子さまの婚約相手・小室圭さんの母が頼る霊媒師の存在
Title: Princess Mako's fiance, Kei Komuro 's mother believes in/depends on psychic.
[...]
Thanks. The article was posted July 2017. If the religious organization was that troubling I don't see how the IHA could have gone ahead with the informal engagement announcement and press conference in September.
If the magazines are to be believed, the IHA and Akishino family took action following the money dispute reports.
Jprime
眞子さまと婚約者・小室圭さんの「結婚延期」に借金トラブル被害者が胸中告白 claims Kei visited the Akishino residence January 6, 13, 14, and 19. Mrs. Komuro also visited on January 19. Princesses Kiko and Mako visited the Imperial Palace on January 20th and the decision was made to postpone the wedding. However, Mako and Kei did not move until after February 2 when Their Majesties had dinner with the Akishino family. It is speculated that Empress Michiko edited Mako's statement because "充分" was used, a term/phrase associated with Michiko. The IHA usually use "十分" in documents to express "sufficient".
The Akishino family will move into a temporary residence while their current home is renovated in preparation for abdication and the prince's new position as "koshi." Since Mako was to be married this autumn, she wasn't given rooms in the temporary residence and that had to be quickly updated.
news-postseven is dragging CP Masako into the drama. It claims Masako voiced concerns early on about Mako's boyfriend. Allegedly she could foresee trouble ahead because she worked in the real world before joining the Imperial family. However, the situation was difficult to know for certain as it's truly another family's business.
CP Naruhito and Prince Akishino are born royals and usually isolated from the general public. Princess Kiko had a short time in society before marrying.
Nifty reports some anxiety among royal watchers when Mako attended a movie screening with her parents on February 16th. The trio walked into the theater in order of Fumihito, Kiko and Mako but the parents swapped seats leaving the prince sandwiched between wife and daughter. A royal watcher sensed some distance between Kiko and Mako. (IMO, not a big deal. The CP and Akishino families have sat "out of order" before. Can't conclude a rift.)
CP Naruhito and Prince Akishino met with Emperor Akihito on February 14 for their monthly meeting. CP Naruhito departed the Imperial Palace at 13:30 whereas Prince Akishino didn't leave until 14:45. Empress Michiko had business at her alma mater University of the Sacred Heart that morning, returning around 13:30; it's speculated Prince Akishino needed to consult with his parents about the postponement. An IHA "source" says it's too long of a chat if the marriage is simply "postponed."