Why is it so hard for some men to show their feelings?

My boyfriend tells me he loves me and he absolutely shows it in my opinion and makes me feel loved, but he said “I’m not very good at showing it”. I’ve reassured him and have told him how he does show it but he still feels he’s not good at expressing his feelings. Any advice on how to get him past that?
Why is it so hard for some men to show their feelings?
Post Opinion