why do guys have a hard time expressing their feelings? and then lie?

so I just went through, and still kinda going through a very confusing situation. I have a guy friend who has trouble expressing his personal feelings and his feelings toward me. we r very close (been best friends for 11 years) and we do have some love for each other but he cant express what kind of love he has for me. then when we're together alone in person he's usually shy and doesn't know what to say. then when we r with other friends he still kinda avoids me yet is still being outgoing. and when we text I can tell when I asked him something and he answers back he's either lying or not telling me everything. (ik him too well) what's up with guys not being able to express themselves and their feelings? and y is he so shy around me and lies when we text.