Situation 01 · "He didn't even call me"
You'd agreed to meet on Friday — over at your place, hang out, nothing special. By evening: silence. You send a quick "where are you?" — no answer. You call — no pickup. It stays that way through Sunday. By Sunday you're in flat anger: "yeah, of course, doesn't care, doesn't need it, and I'm always the one running to him first." You scroll through, in your head, the number of times you adjusted, drove over, waited, rescheduled. That same month, you didn't call your father, as you'd promised. When you remembered on Tuesday, you shrugged — "had a lot going on" — thought, I'll call back over the weekend, and forgot again.
✗ The wrong way out
Prove to yourself that "mine really was more important" — assemble a mental ledger of your tasks, lay them out, hand down a verdict: my putting-it-off is excusable, his isn't. Or, the other way around, drop into self-flagellation: "I'm like that too, no right to be upset." Both versions are an attempt to polish over the asymmetry rather than see it. The first locks the double standard in place, the second just flips it. Neither one returns you to the friendship.
✓ The right way out
Notice the parallel. Not excuse the friend — just allow that he, too, very likely has his own inner movie of traffic, tasks, and "I'll call back over the weekend, then forgot." By not calling your father, you put him in exactly the situation your friend has just put you in. This doesn't cancel the upset — but it brings the hurt down to its accurate size: "I'm disappointed he didn't call" instead of "he's a bad person." And then the simple thing: write to him first, calmly, no grievance. And call your father.