Head job help

I've been with my partner for almost 7 years this year. I have literally given him about 5/6 maximum head jobs/blow jobs whatever you call them and I hate it!! I seriously hate it, I can't stand sucking dick!! I honestly have tried to enjoy it but I just don't. My twin sister prides herself on her dick sucking abilities but I just dont get it. Is there anyway I can enjoy it? I would like to please my husband I know he enjoys it, he has never forced me to do it never, not once. which makes me feel bad as he absolutely loves to give me head and I love it. I just feel bad I can't return the favour as I usually start gagging and dry reaching when I do. I don't want to be selfish lover. Anyone have any tips for me?