This book outlines "attachment theory" - how people express themselves in relationships falls into roughly three buckets:* Secure: doesn't have any issues expressing love* Anxious: is more of the "clingy" type * Avoidant: is cold, tends to withdraw or easily break things offBasically if you're a secure type, you're all good but if you're an insecure type (anxious or avoidant), and your partner is also an insecure type, you're probably going to experience some relationship issues. Actually the book goes one step further and basically says "if you're both insecure types you're probably never going to be as happy as you would be if you dated a secure person, but whatever". A bit of a spicy take but could be true though.
Some of the criticism I saw previously when reading reviews for this book is that it's pro-anxious and anti-avoidant. While I did feel that vibe a bit (the author definitely seemed a tad more sympathetic to anxious types) as a self-diagnosed avoidant I didn't really feel personally attacked or anything. If anything I could agree with a lot of the things the author pointed out (although reading about it is one thing, actually putting it into practice is a hell of a lot harder...).