[aephi alum]

Put his fraternity aside for the moment. Set aside the fact that you are not currently entitled to wear his fraternity's letters.

Do you love him?

That's the question that you need to answer. Do you love him for all that he is - or do you just "love" him because he's a member of XYZ fraternity and you want to be able to wear his letters?

You have made the commitment to moving in together. That's a huge commitment. You don't just move in with someone you don't have feelings for.

Now, if you're really so hung up on being entitled to wear his letters... he can inquire with his fraternity about whether he can lavalier you after he's lavaliered someone else, or whether he can pin you, or whether you can wear his letters after you're engaged or married (if your relationship progresses to that point). Different fraternities have different policies.