yeah that can make it tricky. could you maybe ask him to watch dominion(cw: extremely graphic violence) with you - framed not necessarily as trying to convert him but at least to make him understand why its so important to you? so he can at least try to eat vegan meals with you at home?

i havent gotten my partner fully vegan yet (though shes really close now) and she will still eat meat stuff sometimes when im not there because shes really paranoid about health stuff, but understanding that its important to me has meant that she will always happily eat vegan with me at home. discovering and cooking really delicious new vegan recipes together has been a big thing towards getting her in the right direction (pickuplimes is my favourite vegan recipe site btw, theres so many good and quite easy and cheap things on there). cos if he comes to appreciate that a lot of vegan food is actually tasty as hell, he might be easier to convince