Being a vegetarian vampire would be hard. Especially when you have to interact with potential food sources every single time you go out. It would be like being hungry and hanging out at a party talking with perfectly grilled hamburgers. Okay probably not. I think you can only have that experience if you are really really high. So maybe in Colorado.
I read that whole Twilight series where they are constantly calling themselves vegetarian vampires because they don’t eat people. Of course then they go out at night and hunt mountain lions and bears for blood. That kind of irritated me. Leave the poor mountain lions alone you glittery jerk. Buy some cows and drink their blood. There are whole tribes of people in Africa who do that and the cow is hardly harmed at all. I watch a lot of documentaries.
Anyway my point is that being a vegetarian vampire would be hard. I bet it would be even harder on the other vampires though if that vegetarian vampire got all preachy about it though. Still writers like to use the vegetarian vampire idea in their novels to make the characters more palatable (pun intended) to their readers. After all it’s hard to sympathize with a character who’s supposed to be the hero and is running around ripping throats out and being gross.
It’s even harder still to picture that same vampire as a love interest in one of those Teen Paranormal Romance novels that my wife buys by the metric tonne. Twilight would have read much differently if Edward Cullen would have had no self control and would have been casually ripping people’s throats out and draining people dry in messy ways. Although I won’t lie, if that would have happened I personally would have liked the story better. But then I was kind of hoping Bella would have been eaten at some point.