My boyfriend is not exactly what my parents wanted for me...?

I met this guy at a Christmas party he is in the army 6'6 and has tattoos the one thing is though he is 7 years older then me about... I am 21... My parents said if he makes me happy go for it and do what makes me happy... The issue is I know they are not happy I see the looks and hear the rudeness in their voice... Everyone else in my family loves him my Grandma adores him... She even said I hope you two get married... I have no idea what to do with my parents though cause I love this guy but my parents approval would be great too...