Most people suck at intentional relationship building. I was not an exception.
Experienced entrepreneurs value intentional relationship building. It comes with many names: "build a relationship with your users", "stay close to your users", "build a community", "build an audience"... They all sound vague. But the reason why they are so vague is that really there are a million ways you can build relationships (just like making friends).
You can't build a killer product without a couple of good relationships with your most active users.
I can't teach you HOW to build relationships with your users here, because there are too many ways and situations. But I can show you how I built relationships at Gumdrop (our users are college students who are looking for friends).
One of our most active users, let's call her Jennifer. She is a freshman, new to UT Austin. The first time I meet her, I was ordering food and she was taking my order. We exchanged numbers, and she downloaded Gumdrop (IMPORTANT: She downloaded it not because I was her friend, but because she doesn't have enough friends and she needed more. You can't turn friends into users, but you have to turn users into friends).
I invited her to my parties, and we became good friends. I introduced her to many of my friends. I make sure I hit her up on Snapchat when I see funny or cool stuff. I video her sometimes to catch up. I treat her the same way I treat my other friends.
From my dev perspective:
Users like Jennifer, power our product iteration cycle. If we don't have relationships with our users, we would not be able to constantly test our product and iterate.
You will probably have to build relationships with your users differently: Twitter, Linkedin, indie hacker, online/offline, wherever you can find them. There is no single formula that works on every product. You will have to find your way. Nevertheless, it is a must.