Most Jackson dealers should have a demo Dynamic Duo available or at least point you in the right direction. What state and city are you in, Maybe I can help.
I respectfully couldn't disagree with Flipper42 any more.
I'm an ACA instructor and have found in teaching my 8 year old daughter to kayak that the Duo is one of the best learning aids around. I can take her on runs that would normally be out of her comfort range in a safe manner. Teaching strokes I am right behind her and can see what she is doing well (and what she needs to work on). Teaching boat tilt when peeling out and catching eddies can be a hard concept. When in the Duo, I can set the angle and edge and she get's to feel what it is supposed to feel like. I can also tell her to take the final strokes over the eddy line that many beginners don't do and get flipped going into the eddy. She has gotten used to driving hard into eddies in her own kayak (Fun 1) from this practice in the Duo. So I would say a Duo is THE BEST tool to learning kayaking next to just spending lots of time in your boat on easy water practicing challenging moves. IK's or duckys just don't paddle the same and while they are time on the water which is good, being in a real kayak is the best to learn balance, edge control and strokes. IK's can also lead to a fear of being upside down and even a hesitancy in doing a wet exit, very basic skills in a kayak that should be fun and not feared. If you can learn to do a wet exit, then transitioning to tuck and hang on while your partner rolls you up in a Duo can be very fun and liberating and teaches you confidence and comfort upside down in a kayak. Even better you can really work together rolling a Duo and use this to build skills that will translate into rolling a kayak independently over time.
Now from my perspective I'd rather be in my play-boat on easy water. But, I have found the Duo to be quite fun to paddle. Surfing small (and large) waves is really easy and a blast. Splating rocks, boofing rock and wave-trains is fun. Working to catch small (for a Duo) eddies and making attainments and fast ferrys is fun also. Once I reset my goals for paddling the Duo it became a ton of fun. Even on big water in Idaho with my daughter or a paddling peer you can have a wonderful time on the river and always find a way to challenge yourself.
It is heavy but trying to carry two kayak's is heavy too and that should not be a surprise.
I'd say go get in one for yourself, take it down something easy with a skilled friend in the front. Once you get a feel for it then take another lap with your girlfriend. Make sure she can wet exit properly and with confidence. Then go have a blast!!!