there's no issue I want the best for him but he is stubborn and always goes with cx j so its hard to break habits
Those are common issues beyond a certain age.
Which is why I am saying, don't risk your relationship. If anything goes wrong with JAL F, that memory can become deeply engraved, along with who's idea it was.
I know you want the best for him, but it's not always what you think it might be. Once he experiences F, he might be open to a suggestion, don't push it. Is CX J non-stop bad? JAL F might be a far superior product, but it involves a connection.