Boyfriend has much lower libido than me

An

So I’ve always loved sex. In fact, I’ve always cheated on previous boyfriends because I love sexual variety. Cheating is an awful betrayal, I know, but I just need to give you an idea about how high my libido is. I’m 26 now and started having sex when I was 17, and I haven’t gone more than 1 month without having sex.

I’m currently in a really amazing 2.5 year relationship where I have been completely faithful to my boyfriend. But since the beginning of our relationship, I’ve noticed he’s not as sexual as me. Now that we’ve been living together for a year, I’ve really noticed! We basically only get it on once a week, even though I’ve told him I would be so happy if we got it on 3 times a week. We’ve had many discussions where I say I want more sex and he says he is tired from work, wants to relax and watch sports and just plainly isn’t as horny as me.

I’ve asked him if he would ever consider opening up the relationship since clearly he doesn’t want as much sex as I do, but he’s not open to it. He just doesn’t understand why anyone would ever want to have sex with someone they’re not in love with. I’m starting to freak out a little. I love him so much and think he’s such a perfect match for me in every way except sexually, but being so sexually unsatisfied will probably only lead to my resentment of him along with issues of self-esteem due to feeling unwanted by him.

Does anyone have any ideas on what I can do to try to get him to open up his mind re: open relationships or at least threesomes? He’s very traditional, loyal and stubborn, so I need help trying to convince him of how important sex is for me.