Howdy and Welcome to this Forum!
My Point of View?
The size of the boat you can handle is dependent upon your:
1. Skill and Experience with Boats and Sailing
2. The conditions where and when you sail (bad weather
, etc.) For example, handing sails
in light winds is much easier than in places where the wind
is 20+ knots regularly. The bigger the sails
, the bigger the force you will deal with when the wind
3. The use of auxiliary motors (engine).
4. The level of risk you feel when docking
a boat amongst other boats in crowded marinas
or maneuvering among boats in crowded harbors. Practice makes perfect.
5. The level of risk you are willing to take.
Some people who have lots of experience sailing, motoring, and docking
boats may have the skills and confidence needed to manage a larger boat. Some very skilled couples (or individuals) can manage big boats and may make it appear easy (or say so on a forum).
While some others who have lots of confidence, but little skill, may try and get away with it much of the time, and depend on insurance
at other times.
Aside from one's budget
, I think the most common determining factor is one's sense of confidence (best derived from experience).
Someone who is lacking confidence (due to lack of experience) will likely have anxiety docking, sailing, or motoring any size boat. So, those boats may be bought, but probably spend most of their time in the slip and rarely sailed, unless with a larger crew to help with the docking and such.
The good thing about this?
When you do get a boat (of any size) and spend time practicing those things it requires (sail handling, docking, anchoring
, etc.) you WILL develop experience (and hopefully skill too) and that will increase your confidence and lessen your anxiety (we hope).
I have sailed a bit, so I would feel comfortable as a couple on a boat of 40 feet or so in most conditions. In some conditions, that size boat will seem VERY BIG if one is struggling with some big hanked on sails on the foredeck or trying to lift
a big anchor
manually (no windlass) or if one is trying to dock
it in a cross wind. But, it can be done.
Since you are speaking of a couple, I also suggest you consider what level of comfort you would feel handling the boat (of any size) IF your partner is not available. In those cases, where you are "single handing" the boat, would you feel you could handle a sail change, reefing, docking, etc. Those occasions may not happen often, but could. The good thing is several things can be done to make a boat easier for one to handle it. Some require simple changes to methods, some require a bit of gear
and some require a different way of approaching problems.
Good luck on your choice of boat and happy sailing!