Seven years is pretty big difference,among our parents most common to see coupls who were born the same year.And,as to friendship,one thing,when man or woman have old friends of opposite sex,and know for sure,that thay not attractive for each other in sexual sense(only in this case they can be considered as 'friends',if even they stayed last couple on the Earth,they would never thought about another type of relathionships,because find each other not interesting as man and women),another thing,when man already found women,but continu to search "friends".