I do not think it is appropriate to either marry or date your cousin. He is a family member who should be considered ad a birth family member. Some people consider marrying their cousins as long as they are not their first cousins.
people in the a long time ago would marry there cousin if the population was low in their town and this was way back in the wild west so the town would still have inhabitants but nowadays no its really not necceasry
You cannot legally marry a family member if they are closely related to you, as in 1st cousin or closer. If the person is your 2nd cousin or more distant, then yes, you can legally marry them. Technically you can "date" anyone, as in "go on a date" but as newbuddah13 said, "it's just wrong".