In July 1995, Maryanne Pilling, 48, and Tommy Pilling, 61, tied the knot in a lavish ceremony at St Mary's Church in England.
The pair had set up a Facebook page to provide a glimpse into their solid marriage after their 22nd anniversary together.
But five years ago, Tommy developed dementia, leaving Maryanne fearing he may be taken away from her, The Sun reports.
According to the reports, the effects of the dementia have become so bad that he sometimes forgets who she is, leaving Maryanne "hysterical".
Maryanne's sister Lindi Newman, 31, told the Daily Express: "He's forgotten who Maryanne is a handful of times.
When the couple first met, Maryanne couldn't stop raving about Tommy. Photo / Supplied
"It always happens really late at night. He pushes her away and says, 'I don't know who you are' and 'I don't love you'.
"Maryanne takes that to heart and is absolutely crushed and hysterical."
Lindi says she has tried to reassure her sister that his health is just going through a phase and that it will improve.
The couple set up a Facebook page to celebrate their 22nd anniversary but now Tommy has difficulty recognising Maryanne, leaving her "crushed". Photo / Supplied
Maryanne has become so worried that she won't be able to join him in residential care.
Describing how they met, Lindi previously said: "The day Maryanne met Tommy she came home with the biggest smile on her face.
Maryanne and Tommy Pilling have spent 24 years together but this Christmas may be their last if Tommy's dementia worsens. Photo / Supplied
"She couldn't stop talking about him and asked if he could come for dinner.
Lindi "received a lot of flak at the time for letting them get married but she insisted it was their decision."
The pair dated for around 18 months before Tommy popped the question.
Tommy and Maryanne Pilling are facing a possible separation due to Tommy's dementia. Photo / Supplied
They recalled strangers "pointing and staring" at them in the street, while others insisted people with "learning difficulties shouldn't get married".
But Maryanne had dreamt about a big white wedding since she was a little girl.
Maryanne Pilling and Tommy Pilling have been "blissfully" married for almost 25 years. Photo / Supplied
As the couple's 25th wedding anniversary approaches, the family worries that Tommy won't want to celebrate the milestone event or be able to remember it.
Lindi told the newspaper that even though the couple would need to be separated if Tommy required residential care, the family would "do whatever we could to stop it happening."