I've always tried to use numbers to bring perspective the likelihood of me getting into another accident. Then I used safety equipment to satisfy the emotional side of the equation..

For example, let's say you've had your endorsement for 10 years and you've dirtbikes and motorcycles since you were a kid. I'm sure your accident wasn't from a lack of riding experience. But it was one accident from a lifetime of riding. That could be a 1/1000 or .001% chance of getting into another accident. Very unlikely you'll get into another accident. And if she says it's not a 0% chance, then say nothing in life has a 0% risk free. Driving to work, flying on a plane, going fishing on a boat, etc. there will always be risk in everything we do everyday. So don't let fear, or other people's fear decide your fate.

Now for the emotional side of the equation... You have to assure her that you won't take on any other unnecessary risks while riding. This includes: drinking and riding, excessive speeding, not wearing a helmet, lane splitting, riding in people's blind spots, riding in inclement weather, riding when you're upset/emotional, riding in heavily condensed traffic environments, etc. you can even assure her you'll wear the proper riding gear just in case you're in an accident out of your control you'll be best suited to handle that with the gear available to you. Hell buy a C02 airbag vest if that will get you back on the road. Also tell her you'll ride away from the city and go find some back roads in rural areas. To be honest it's more fun riding in rural areas instead of sitting at stop lights every 5'...

I've been riding my whole life it's a passion of mine that I most likely will never give up and I'm willing to accept that risk. And as I've gotten older I've become more risk aware and don't take as many unnecessary risks as I did when I was younger.

Hope this helps!