What is the difference between "in-between" and "in between"?
Solution 1:
According to Merriam-Webster, 'in-between' is used as a noun or adjective whereas 'in between' is an adverb or preposition.
Hope this helps.
Solution 2:
I think the correct form would be actually:
The man is sitting between the two women.
So, neither. You are using between as a preposition here, so if you refer to the questions you gave as examples in your question, you should use just between.