In the case that he is willing to try the vegan dishes that you prepaire, it's settled. Or like some people, gradually move towards vegan meals, first less meat and subsitute the animal products with alternatives like beans, tofu or mock meats, then get rid of dairy and eggs. Or however is the best for him. Communication is important, he'll tell you what he wants if you ask. That's all the advises I can give.
Here is some real life story:
My boyfriend whom I have been with for over 6 years now will not want to eat vegan food. He is very picky eater, without exception eats the same foods, week after week. And that is not the end of the world or even our relationship. The meat, eggs and dairy disgust me. But when I prepaire him food I take this kinda mindset that it's similar to making food for a cat. You just do it for the one you hold dear.
Secretly, inside my deepest mind I hope that he someday comes around. He is such a kind heart and I'm sure that had he the time and energy he would deffinitely understand that feasting on animal flesh is not the right way to go.
He is willing to listen when I tell him about the horrors of animal agriculture and is always supportive.
I show him that being vegan is delicious, easy, inexpensive and healthy. Once he tried some of my food and actually liked it.
It creates internal confliction to cook non-vegan meals, which is why it's of utmost importance that he is 100% worth it. Sadly, you can't expect that the minute you go vegan, the whole world around you also does and you can't ignore all the meat eaters forever. You have to be strong for it can be depressing to wake up in this realization. I'm immensely grateful for this forum, books like Vegan Freak and vegan activists on YouTube, those I find empowering.
No matter how small impact you have on those around you, atleast you stay vegan. That means less suffering for the animals. Sometimes you convert people vegan unintentionally, like I have. You don't have to be pushy with veganism if that's not you.
I wouldn't cook non-vegan for those whom I don't care about but in this particular instance where it is my loved one and I can almost understand where he is coming from and why he won't change, I will.
I know my opinions and actions are strange. Alot of this is influenced by Anthony de Mello Awareness -that book I have read so much the pages are worn and torn. I find that kind of mysticism more familiar than mainstream scheme of things.