My husband has changed his phone password, and it’s driving me crazy

We’ve been married for 7 years, so everything was out in the open until now, but for the past month, something has changed. He never separates from his phone and has even changed his password. When I asked, he brushes it off by saying they discuss private things at work, but honestly, it doesn’t sound convincing at all. There’s also a coldness between us; we feel like strangers now. I’m even starting to think about divorce. Do you think I’m just being paranoid, or is he possibly hiding something? Is this situation normal?