I am looking for a short story from the early 1970s about a man who is imprisoned by a government and is "frozen" at that point in time. His wife works on a spaceship, hoping to only age a little so that she'll be able to rejoin him when he is let out of prison. Her favorite flower is the white gardenia and he has one waiting for her on her return.
I have identified this book before in Seek SF melancholy story about woman who waits for her partner
You have slightly misremembered the bit about the white gardenia. The protagonist, Philip, doesn't bring a white gardenia. When he returns he finds a white gardenia that his love, Miranda, has left on the table:
He returned to the living room and went into the kitchen. The kitchen was the same too, but there was no Miranda in it. He switched on the light and stared at the porcelain sink, the chrome stove, the white cupboards, the gleaming utility table ...
There was a hand mirror lying on the table, and beside it was a crumpled gardenia. He picked up the gardenia and it was cool and soft in his hand. He held it to his nostrils and breathed its fresh scent. There was another scent mingled with it, a delicate fragrant scent. He recognized it immediately as Miranda's perfume.