About do you guys husband so secretive when he was chatting with his aunt via by ws

As every time his aunt will whatsapp my husband and my husband super secretive saw me he quickly tells his aunt bye bye on the phone plus he even tell his aunt lots of things he didn’t want to tell me about it. I found it is so rude and ridiculous it seem like he doesn’t trust me as his wife I wonder why must he marry me in the first place?