What are the permissible and impermissible boundaries of the relationship between an engaged couple after the Fatiha (marriage contract has been recited), given that they work together in the same place, and is it obligatory to inform the families about the boundaries of this relationship?

If the marriage contract is valid, then you become his wife, and it becomes permissible for him to do with you what is permissible for a husband with his wife. You are not obligated to inform your family or his family about the boundaries of your relationship. However, the custom must be respected if it does not permit the husband to consummate the marriage with the one he contracted with until she is formally brought to him (the wedding). It is permissible for the wife to refuse to surrender herself to the husband until he pays her the immediate portion of her dower. It is advisable not to allow the husband to be in private seclusion before the wedding, due to the potential harms that may result from it.