Friendships, like all relationships, must be nurtured to survive. A lot of neurotypical people are kinda crap at nurturing friendships naturally but they try to do so often in subconscious ways.
If your social skills are below average you may not pick up on the subtle clues, so you'll have to make more explicit efforts to maintain the friendship, and explain to your friends what kind of gestures go toward nurturing it when it comes to yourself, ie you mostly consider time spent together, or chats, or phone calls, gifts, what have you.
I'm not a psychologist but I'm a neurotypical person with a few high functioning autistic friends if you want my opinion on anything.
Speaking of books: Games people play by Eric Berne was an eye-opener for me. If you want to find a logical framework to wrap your head around social interactions, it is a useful book.
For me at least, I found that watching comedy series helps a lot to figure out social transactions. As a positive byproduct you learn to make jokes, which can also help in your pursuit to become socially appropriate.
I also find that if I stay away from computing for a while, I tend to get more normal.
Putting an effort into dressing acceptably (clean, fitting clothes), getting regular haircuts, figuring out how to chit-chat, generally smiling and nodding are my current strategy to fit in.
On the subject of social skills, there have been many books on the subject, traditionally titled under Asperger's: https://www.goodreads.com/list/show/12108.Top_social_skills_...
Friendships, like all relationships, must be nurtured to survive. A lot of neurotypical people are kinda crap at nurturing friendships naturally but they try to do so often in subconscious ways.
If your social skills are below average you may not pick up on the subtle clues, so you'll have to make more explicit efforts to maintain the friendship, and explain to your friends what kind of gestures go toward nurturing it when it comes to yourself, ie you mostly consider time spent together, or chats, or phone calls, gifts, what have you.
I'm not a psychologist but I'm a neurotypical person with a few high functioning autistic friends if you want my opinion on anything.