Have you thought of one step at a time, instead of the full leap? Like a short cruise for starters, then maybe a craft you can take out for a weekend with the good woman playing first mate? Something you can make payments on until she gets the bug herself and suggests selling the house, the car, the children, the whatever, and hitting the high seas. Edging ever-closer to the dream...I understand that time can seem short during the middle years, as one faces the reality that one day, should life extend so long, one won't be physically able to slip the moorings, much less hoist sail and all. But half a loaf, etc.
Too, are you asking Madame to leap into the unknown (for her)? Has she any experience in sailing? If not, fear of failure/seasickness and all those death-at-sea stories may be coloring her outlook. If you use some patience, and are visibly proud when she proves to be a good sailor herself, she might come to enjoy the vagabond life enough to begin asking when the two of you can take a longer (and longer and longer) offshore trip.
Just food for thought.
Sarah