Intercultural marriage

My husband and I have been married for 2 years. He is from West Africa and I'm from the US. He has always been on his phone a lot since he has a lot of friends and family throughout the world. Just recently though, whenever I walk in the room and know he's texting someone, he pushes the lock screen on his phone. Anytime I have ever brought up any issues about his phone, he tells me that it's his phone and its none of my business. I have never been allowed to touch his phone. He even has it fingerprint protected. How do i get over this? I feel like his phone is ruining our marriage.