I would start by telling him that this isn't something to be "fixed" - this is who you are - and also ask him WHY he wants to "fix" you.
One thing I would be curious about is if he has any misconceptions about bisexuality. Some people think that being bisexual automatically means you want to be romantically involved with both sexes at the same time and he may be worried you'll be looking for "satisfaction" outside of your relationship.
Or he may just be more bigoted/homophobic than he's willing to admit. If he's not willing to stop trying to fix you, I honestly don't see how you could continue the relationship and have it be healthy.
Hi there, that sounds like a horrible situation to be in, your boyfriend doesn't seem very accepting of your sexuality. Please remember this is not your fault and your boyfriend can't expect you to change because he doesn't like who you are. Keep talking to your boyfriend an make it clear you can't change who you are but that you are still the same person
It sounds like there is something a bit irrational about how he feels: it's not logical for him to have no prejudice about LGBT people, unless it's about you. Trying to reason with him and put things into a logical plan might be helpful. You can encourage him to tell you why does he think it is wrong for you to be who you are, to provide you with a reasonable motivation for wanting to fix you. With time, he will see that his feeling is irrational and he will understand there's nothing to fix. Just make sure you're always open-hearted about how you feel, and reassure him that your love for him doesn't change, nor does your personality. If he will still want you to change who you are even after you did all of this, then remember that there can only be true love with someone who accepts you for who you are.
For a lot of people, hearing about your loved one being with others in a relationship or physically is always a difficult position to be in regardless of your sexual orientation/ identity. It seems like maybe his discomfort with you being bisexual is more related to your relationship and him worried about your attraction to others in general, and less about the gender of the "other" you may be attracted to. Maybe if you talk to him about this it will help you both understand him and each other better. Hope this helps; take care and best of luck! =]
Related Questions: I'm bisexual and my straight boyfriend isn't homophobic when it comes to anyone else but me. He wants to try to fix it but he doesn't know how and i don't know what to tell him. Please help? :(