Someone messing with my device

Have noticed irregularities from iPhone to this new s9 I bought. Such as pictures and text messages I take or send ending up on my girlfriends phone. Not only that I shut service down to every other phone on my Verizon account accept her phone. Strange thing is two nights ago my truck alarm goes off in the middle of the night. I shut it off and it goes off immediately again and I shut it off again and all was well. I just found my s9 in my truck even though I last had it in the house!!! I went into boot mode because the encryption phone pin I don’t seem to have the pin which will force a factory recovery. I took a few pics and will see if I can post. Any ideas?

Welcome to Android Central! Sorry, but we can't really help you regarding the issue of you misplacing your phone or somebody taking it from you, apart from advising you to keep the phone on you at all times, and also making sure it has a good screen lock method set up that nobody else knows or can guess.

When you say that pictures and texts you take or send end up on your girlfriend's phone, are you talking about the messaging app only? Or are you also talking about photos you take with the Camera app? Did you ever add your Google account to your girlfriend's phone at any point?

Do you feel like you are in danger?