Maybe some on entered your wallet without your permission. If I were you, you should maximize the security that your wallet is offering. If they are offering double authentication, make sure that you have activated it so that those hackers that are planning to enter on your wallet will have a hard time since they need an authorization code that will be texted by you.
well if he uses a hard wallet, of course, the closest person can be one of the perpetrators. make sure that no one knows about it, even if your friend, because in money matters if there is an opportunity, they might take it. the problem with crypto is, when you send money, you won't be able to take it back.