So I just got into my first ever relationship. I was always super insecure growing up, and still am. I feel like this is affecting my relationships and need help on how to fix this. I constantly feel like my girl is cheating on me, even though I have no reason to think this. And when she mentions any other dude she's friends with, it fills me with rage. Another thing I do is make up scenarios in my head which make me feel anger and sadness as well. I just feel like I'm easily replaced which is why I think these things. We started dating only a few months ago, but I feel like if I keep getting in my head like this, it wont last much longer. Which I don't want to be the cause because I really like her. How do i overcome these thoughts and insecurities?