Oral sex vs. vibrator

So I had never really been into receiving oral sex before. I was married for 5 years and we always used a vibrator for me to get off. He never preformed oral sex on me. Ever. With my boyfriend now, he loves giving oral and I love it! but I can't seem to get off from it. Do you think it's because I'm so used to a vibrator?! Does anyone have any tips on maybe how I can get off from oral sex?