Every relationship is different. Some couples couldn't be more opposite while others seem to mirror each other's every action. Maybe you perfectly compliment each other and your strengths take the place of their weaknesses. Either way, if you've found someone you genuinely get along with--someone who brightens your day and makes life easier, I believe you've found your person.
Finding someone you'd consider "your person" can feel like you've won at this whole relationship game. The unfortunate truth about relationships, though, is that you're not always going to be with the person you love. People change, outside distractions get in the way and the obstacles of life can strain any relationship. Sometimes it all gets to be too much and your person isn't your person anymore.
When your person is no longer your person, you don't plan your Friday nights around what they might want to do.
When your person is no longer your person, you don't agree with the same things you used to. Why are you arguing over a restaurant choice? I thought you liked what I liked?
When your person is no longer your person, your family and friends eventually stop asking you about them. Yeah, your sister's birthday party -- don't worry about needing a plus one because your family already knows you don't.
When your person is no longer your person, your schedule seems almost empty. You might even hang out with that friend you always said you'd make time for.
When your person is no longer your person, you have to revise those holiday and special occasion plans.
When your person is no longer your person, you forget about those inside jokes because you haven't told them in so long.
When your person is no longer your person, it might seem like you've been spending your time with a complete stranger. They don't really understand you anymore like you thought they always did.
When you realize your person is no longer your person, it's time to move on and let go of the times when they were. It doesn't mean either of you is wrong or right. It doesn't mean your relationship was a fail or that one of you messed up along the way. Sometimes, your person becomes someone else and the only thing you can do is accept the change and believe that there is someone out there looking for their person too.
