Sounds like you've got your antenna up; you are checking for any disturbing airwaves.
More commonly know as "red flags."
This is great and will help you in the future.
I don't think you have to give up on them yet. Meet this woman, be sure you are meeting in a public "vanila" place you are familiar with and comfortable in. You will learn so much more about her, and her relationship with her husband, through a personal meeting. Make sure you have communicated--and gotten confirmation--that you both can always decline setting a playdate if you or the woman don't feel things are meant to be...no questions asked, no explanation needed.
This will be a good learning experience for you. I'd not miss the opportunity. I also agree with ohers that you must directly ask her to explain what she meant about her husband going outside their boundaries. Make sure she understands your boundaries.
Regarding your question on meeting couples online: We met our first couple online through Swing Lifestyle (SwingLifeStyle). We continue to play and they are good friends.
LM