Should I trust him?

I’ve been seeing this guy for almost 10 months now and it’s been going great. We have a great time together we laugh we joke and it’s all round enjoyable. He’s always been secretive with his phone and his life from day dot, but even if it’s just messaging his dad (and I’ve seen it genuinely is). Lately he’s been more secretive than ever and never opens WhatsApp in front of me anymore and I know he still goes on it. I’m start thinking that he’s sleeping with other women as he goes to the gym a lot but I’d like to think I give him everything at home! He definatley doesn’t go short. I then question if there something wrong with me as I’m the same woman he goes to bed with every night. Help a mama out please ladies xxx