How can you stop being crazy and insecure in a relationship?

I’m very anxious while in relationships (I think it’s typically because I have a hard time maintaining relationships in my life in general because I’m super independent and find being alone peaceful) however I do want a partner. Any changes in behavior from my significant other, and I think of worse case scenario. It has gotten to the point where I felt like my partner was cheating on me today because his location for darts he does is different today than usual but I found out he is actually at darts. I really don’t know how to shake this feeling, and I don’t want to lose my partner because of it, but it is a me issue and I want to work on it, don’t really know where to start. Any suggestions?
How can you stop being crazy and insecure in a relationship?
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