The book, "The Friendship Factor: How To Get Close To The People You Care For", is about close relationships that is often called friendships. The subheading explains the main purpose of the book: How To Get Close to the People You Care For.
Intimacy is something that is difficult to develop but well-worth the time and energy to develop. Friendships without any degree of in-depth intimacy are just acquaintances. There is a process of developing friendships. It is more of an art than science. This book discusses reasons and factors on why you should have friendships. A variety of friendships is good for the enhancement of all your relationships.
The book has an interesting perspective that can help any relationship. It is about overloading your friendships into one person. Most people would approach friendships based on similarities such as relatives (family similarities) and then expect (with emphasis on expect) that all facets of that particular relationship to be aligned and bonding. That is not the case. You can not have one person be everything for you to the point where if that person does not fulfill that role then the friendship is doomed.
The "Friendship Factor" discusses having a variety of friendships based on different interests. You may have a group of friends who enjoy fishing or reading classical books. You can stay within the realm of that relationship based on the commonality such as fishing or classical books. Your "fishing buddies" will serve the purpose of fishing. You do not have to talk about your job with these group of friends. With the expansion of on-line communities, it is easy to meet other people with similar interests (though you have to approach this path cautiously and discretion).
It places tremendous burden on one person (eg your spouse) if you expect them to have the exact hobbies or thinking. Instead, you should consider that "variety is the spice of life" including your relationships. As a pre-caution, the type of activity can reflect on the quality of that relationship. Drinking buddies may not be the best type of friendships as it could get your in trouble such as driving under the influence. The type of activity reflects strongly on the long-term quality of that relationship.
Friendship is by choice not be chance. You have the choice to choose who to be friends with. This book gives tools to expand or enhance those friendships in your life.