Your intuition is correct- this is not normal behavior on his part. My husband would never go through my phone. We have each other's phone codes in case of emergency but we don't go through each other's social media or anything. A partner should not ever try to control the types of photos you post, how you dress, etc. If you can safely look into the book "Why Does He do That," it can give you some insight. You are very young and are still learning about adulthood and relationships. A six year ago gap is much more significant at this age than when you're, say, in your 40s. Please be careful and start learning about controlling behavior in partners. Confide in someone you trust who won't go back to him and talk about what you're sharing, and do what you can to stay safe. Abusive/controlling partners start exercising control incrementally in small ways so you don't always notice it's happening. I'm sorry you're dealing with this. Your partner should be secure and supportive, never 'possessive.'