Overthinking will ruin your relationship, because it means you are not talking to each other. It means you are assuming what your person meant when they sent a certain text or used a certain tone. It means that instead of feeling comfortable enough to ask them a question to get clarification, you are choosing to guess what has been running through their mind to avoid a conversation.
Overthinking will chase away your forever person because it makes it look like you think the worst of them. You are probably paranoid due to your own insecurities, but it doesn’t seem that way from their point of view. If you are worried they are cheating every time they come home late and worried they are making fun of you every time they smile at their phone — then it looks like you don’t trust them. It looks like you think they are heartless and willing to hurting you.
If this person really is your forever, then you should be able to talk to them. You should feel comfortable sitting them down and having an adult discussion. If they are the right person for you, they are not going to be turned off by hearing about your feelings. They will want to know what has been bothering you. They will be happy to answer any questions that have been nagging you.
You need to talk to your person, because if you keep guessing what they are thinking, half of the time you are going to be wrong. Half of the time you are going to stress yourself out over a problem that does not even exist. Half of the time you are going to make your life harder than it has to be — and you could ruin your relationship in the process.
Think about it. When you have a fake argument with them in your head because you are convinced they did something to upset you, how do you react? You get quiet. Or snippy. Or defensive. Or angry. And your person has no idea why you are feeling that way, so they react in anger and then you’re suddenly in a fight about nothing.
The healthy move is to communicate with your person. If they say something that sounds suspicious, ask them what they meant. If they come home late and you have questions, ask them. You will be surprised by how many of your worries vanish once you create an open discussion.
You cannot keep letting yourself overthink because you are driving yourself insane for no reason. Instead of jumping to the worst case scenario, take a breather and ask your person about what has been bugging you. If they are your soulmate like you think they are, then they will be happy to clear everything up. They will be happy to calm your fears.
And if you’re dating the kind of person who fuels your paranoia, who refuses to answer questions and jumps down your throat whenever you express emotion, leave. You are in the wrong relationship anyway.