Do you have experience living full time on a small boat or in a tiny house? I'm a solo sailor, and 32' is right at the floor of what I could do (at least as a "liveaboard"), comfortably. I'm fine on a pocket cruiser for passages, but when you're living there full time, comfort and living space becomes more important.
For one thing, stuff like closet or storage space for personal items becomes an issue on a small boat. I don't have a ton of clothes, and I barely have enough closet space just for my stuff. The head is also tiny, and unless the woman is used to the lifestyle, I find females tend to need more personal hygiene space and they find my 32' too cramped.
Another thing to consider is that more and more municipalities in the United States are making it more difficult for people to live on boats. It's actually getting ridiculous in California. Many Marina's have quotas on how many people are allowed to live aboard, and that number seems to get smaller every year--and if it's in a popular area, the wait list could be unreasonably long. Some people do stealth live aboard, but if you get a pedantic neighbor who tattles on you, or someone who just wants to be a jerk, this would be a headache I know I wouldn't want. If you're in a salt water area you could just find some place to anchor (and move every week or so), but on a lake you'd have no place to escape to if the authorities decided to start hassling you.
Just a few thoughts in case you hadn't considered them. I know of couples who are perfectly fine on a small boat, and you may be one of them, but personally I wouldn't want to live aboard with another person on anything smaller than a 36 footer.