What is your communication like with real friends?

This question may go alongside what is a real friend or a best friend. I am in college and when I started I gained some close friends that I thought would be lifelong friends. My parents and others always told me that the friends you make in college will be friends for life. Everything seemed great when I lived on campus and was taking classes with the people I consider my real friends. However, when I got a co-op and started working full-time at a company every other semester, things began to change. I moved home to save money and because it was closer to the company than my college campus. When I moved off campus, I stopped hearing from my friends. I would always text or call them, but I would get short answers and they would never initiate any communication. I wouldn’t get invited to events. It was like once I moved away, I ceased to exist. Since I was working full time and now lived around an hour’s drive away from the campus, it was hard for me to be on campus a lot and I was often too tired to go to weekday parties or events. My birthday was also during this co-op period. I thought maybe inviting them to a birthday get together would make things normal again. We had a fraternity event that day(Some of my male friends were in the same fraternity with me), so I went to that event and thought everyone would just drive to my birthday event afterwards(10 minutes away). To make a long story short, not one of my college friends showed up. The only people who showed up were my few good friends from high school. After this occurred, I really felt like I didn’t have any real friends in college so I focused on spending time with my coworkers at my co-op and my friends from high school. I stopped going to college events and parties and stopped initiating communication with them. Weeks later, I had a conversation with who I thought was one of my best friends and he asked why I hadn’t been seen. I told him the reason and he and my other fraternity members said I should’ve moved the date of my birthday get together since we had a fraternity event beforehand and the night of the day after. I may sound selfish, but I thought this was extremely unreasonable. Since I had been attending less and less fraternity events because of my work experience, they also informed me that they didn’t need me and that business would carry on without me. To be honest, I didn’t care about that(I’m not a fraternity obsessed college student and I never placed heavy emphasis on it. In fact, as time went on in college I stopped wanting to party all the time and preferred to do more chill activities.) I really just wanted good friends. I thought fraternity brothers were supposed to be best friends. I thought college friends were friends for life. When I told some of my other college friends I really missed them at the birthday, a lot of them said they were at the amusement park instead or were just too tired to come. At this point, I really just disconnected myself from everything. I had my girlfriend who is my very best friend. We were best friends before dating and when I cut some of these negative people out of my life our relationship only got better. She was my best friend and always there for me and still an amazing girlfriend.

Now that I’m about to graduate and it’s been two years since all that happened, I’m starting to regret my actions. I feel like I should’ve initiated more with my college friends. There is one girl that I talk to, but even then when I talk to my college friends I am always the one to initiate. I feel like I’ve missed out on a lot and I should’ve just been better and stayed around. I co-oped a lot of semesters and recently concluded my time with the company. I am starting to regret working because of my friend situation and because since I was working full time every other semester my graduation date was pushed back. Now all of those people I knew in college are starting to graduate and I feel like I’ve made some mistakes.

Since all that time has passed, I’ve started trying to reach out to my college friends again, but even though they say they might miss me they never initiate communication and don’t seem to have any interest in hanging out. I guess that it is selfish of me to want to continue relationships with these people after everything that’s happened.

Now that the background is out of the way here are the questions:

Should I continue to try to communicate with my college friends?

My good friends from high school and I still talk and hang out every once in a while, but it isn’t often. When we do meet up, it feels like no time has passed at all. How often do real friends communicate? How often do best friends communicate?

I also feel like I do not have a best friend. My girlfriend is definitely my best friend, but I really want to have a male best friend. I guess that sounds childish, but it’s something I really think about. At this point, I feel like if I meet new people they will already have best friends even if I can become good friends with them. Thus, I feel like my only pool for a best friend includes high school and college friends. How do you find a best friend and determine who is a best friend?

I know this is a lot to read. Thank you for those that do. My thoughts on this are kind of all over the place.

TL;DR
How often do real friends communicate? How do you know when someone is a best friend and you are a best friend to them? Do real friends always both initiate communication? Do you always initiate communication with a friend?