So maybe it is your wife that needs to understand that a better fitting boat is easier for her to paddle - either way take the time while air and water are still warm to sort this out. And minimum deck lines and two bulkheads if you are nearer Boston like it appears. You will want to go into the salty stuff and the minute you try to do rescues you will find out you (and she) want that. Skinnier and longer overall tends to mean faster.
If anything she needs a boat that is faster than yours, since she has the less powerful engine (herself).
Most of the below current/new boats can be found used or at a reduced price before winter hits if it was a demo.
I am not going to include the Hurricane boats because you already said you loved paddling in Maine. So do I, every summer for a lot of years now. And I would not think about trying that layup on those rocks.
I am looking for boats with a max load of more like twice your wife’s weight than three times, a cockpit that is narrower and shorter than would be for you, lower deck. Thigh braces are no good if the paddler can’t easily reach them. You can do this too.
Wilderness Systems, filter for Small Paddler - SINKs are Zephyr 155 and Tempest 165 (someone above already mentioned the Zephyr)
Current Designs - Nothing there for a 120 pound skinny paddler until you get to the specialty British, Greenland etc boats. Squamish might be a go for her, good height, cockpit dimensions and improved overall volume (250 lb max) for her. I tried looking in Greenland style, used to be at least one good fit there, but the link keeps sending me to the Danish boats.
Having a bit of trouble with some like Venture, can’t determine a useful cockpit size for her.
You can do a Small paddler filter at Perception’s web site under kayaks.
And there are older models, available used if you look around, that are good matches for a paddler her size. But you might find one or two of these at an outfitter, being tuned around as used boats that she could sit in. So start there.