My husband changing his phone password

So, normally we girls would know each other's passwords and it wasn't a problem at all, but for the last few weeks, she's been leaving her phone around less and less. I saw yesterday that she changed her password too. When I asked her, she said something about work, but honestly, it didn't sound very convincing to me. She's been really cold for a while, not even touching me; I wonder if there's someone else in her life or if I'm just being paranoid. I'm going to lose my mind.