Question

can a best wife play role of best friend​

Answer 1

Wife is someone who can be a mentor of her life partner in his difficult time.
A best friend is someone who can also advice is friend about the good and bad things of life thus helps him to make difficult decisions with a good advice.
Thus, wife can definitely play the role of a best friend of her life partner.

Answer 2

Study: It is good to date your best friend
The study found that the "well-being effects of marriage are about twice as large for those whose spouse is also their best friend." According to the study, women benefit more from being married to their best friend than men do.