An important lesson that took me my entire 24 years to fully embrace is that I am not the standard for what is right and wrong, for how people should and shouldn't react, or for what people should and shouldn't do.
Thoughts like "If he loved me he'd do this" or "If she was sorry she'd act this way" often actually translate to "If I were him and loved me I'd do this" and "If I was sorry I'd act this way."
This sounds simple but it's so easy to forget since all we've always known is the way that our own mind operates and the way that we react to things. I've been trying to remind myself to stop and think about how HE or SHE would actually react rather than how I would before getting upset.
Because you can't expect the best version of yourself from other people, just the best version of them.
We are all so different. We have different love languages. We've gone through different experiences that have shaped our minds to think a certain way and trained our brains to interpret things differently.
Remember to ask yourself things like "Are they really not showing me love or are they just loving me their way" and "Are they really not sorry or is their way of showing they're sorry just different than mine."
This way of thinking can help you to better understand the way your significant other loves or to look at a family member you've never seen eye to eye with in a different light.
There's a big, big world out there full of varieties of people who have unique ways of loving and arguing and living. Most times, these different ways aren't "wrong." They're just different.
So if you care for someone, sit down with them and ask them why they think, act or react a certain way about something before getting upset with them. You'll be surprised how much you learn about other people and yourself in the process.