Are there common/well-known (and hopefully curable) reasons why a plant's flowers would fail to open?
The plant in the pictures below has remained in the same earthenware pot - about 45cm at the top, tapering down to 30 cm, and about 40 cm tall - for at least the four years since I inherited it along with a property purchase.
Notice that none of the flowers have actually opened - they've actually been that way for a good four weeks at least. The same is true of the entire plant: not one flower has actually opened! Some have even started wilting without having ever even opened - as in the first picture. I'm almost certain this is the first year the plant has behaved this way - I'm nearly sure the plant was "unexeptional" last year, just going through a "normal" cycle of flowers budding, blooming, and dying.
What are reasons this might be happening? And is there anything I can do to help the plant get back to being healthy?
Also, I'm curious if anyone can help identify the plant. The plant is in southern California, but I have no idea if it is native to the area. I don't think I've seen it anywhere "out in the wild" locally.
Update: As requested, posting a fuller profile pic of the plant with non-opening flowers:
Here's a picture of its neighbor plant - not five feet away. Other than the neighbor plant's flowers being more fully pink than the "sick" one's white/pink mottling, I'd have said they're the same type of plant. Interesting that the healthy one grows far more upward than outward, which the "sick" one seems to prefer.