I know all about those feelings of being "suckered." A lot of mine came from staying in a dead-end job too long or spending way too much time and
money keeping old cars running.
I restored a 66 Mustang and drove it for four years thinking, this thing is going to be so great when it's all finished and reliable. Yet, even once every part of that thing had been replaced, it still had a new problem that required at least one weekend a month to
repair it and keep it running. It wore me down and became a hassle instead of a joy. Eventually it ended up shut in the garage and sat for two years before I could bring myself to sell it, but letting go of that gave me the ability to pursue other interests.
Boats are like that car. There's no, "I'm done with the work" point. There's no, "It's finally reliable, no more repairs" point. However, you have to remember, everything that you go through with it is knowledge. It's lessons learned. It gives you subject matter expertise and enables you to be that much more self reliant.
If working on your boat is no longer fulfilling, maybe you've learned all you can learn from this life experience. What's is telling you? Perhaps it's time to take all this knowledge and use it to find a newer/larger/different boat that would be a better fit. Perhaps it's time to downsize the boat to a weekend cruiser and invest in a condo nearby that requires zero
maintenance, so your time is freed up for other jobs/hobbies/interests.
Then again, as Anjou mentioned, the feeling of being worn out may come from not being fulfilled in your job or unhappy with your
current role in life and that's just being taken out on the boat. I have no idea if you
work or not, but if not, a job or volunteering with an organization can do wonders as far as giving your life a feeling of purpose. If you do work, and you're miserable, go find something new. Lots of people feel trapped because they've been in a job so long, but they never actually look at what's available.
Definitely communicate all of this to your partner. The worst thing you can do is nothing and just keep bottling up the feelings because eventually it explodes.