Why is he so frigid? How do I make him feel comfortable?

Ok so i've been friends with this guy for a year and he's always been a ladies man. He's funny, charming and seems to have the prettiest girls falling for him even though he is not very good-looking (not in a bad way). He's created a 'stud' persona and used to imply that he was sexually experienced, he never said he was I just assumed he was. He's an extremely loud and confident guy. Anyway, I saw him out a couple of times and we started talking A LOT over the phone, on the internet etc and then after a year we both admitted we had feelings for each other. It was then that he showed a different side to himself as a more vulnerable person, and he admitted that not only is he a virgin but he's also never kissed a girl! I was shocked because he's always surrounded by girls but he joked that it was because he's never met a girl up to his standards. We went on our first date and straight away I knew something was wrong, he didn't seem to know how to interact with a girl, and seemed sort of stiff. He had his arm around my neck but it felt weird like awkward? Like not romantic and then he tried to kiss me and it was so embarassing and awkward I backed away. Whats up with these different personas?! What do I do?! I'm too embarassed to meet him again but I really like him. He's gemini if it helps, and we're both 18.