I've found that the concept of love languages helps pretty much any relationship, not just romantic ones. It's useful to understand what matters to people.

For example, I used to get angry at my brother for being terrible at keeping in touch. He rarely calls, and it hurt my feelings. But then, we'd get together at family events and have long, meaningful conversations, and everything was great. He'd tell me how much I mean to him, and I'd feel reassured. But then he'd go back to being terrible at keeping in touch, and I'd get my feelings hurt all over again.