Sexxit: Anyone out there whose relationship got more sexually passionate with time? In need of hope

I am a 26f who has been in a 6 month relationship with a 30m. When we were just dating casually, there was always great sex, passion and friendly times. He seemed very attracted to me and even adventurous, there was some exhibitionist fun times sprinkled in. He asked me to be his serious partner a few months ago and recently to move in with him. I agreed, but after I got here suddenly the passion died and the sex dried up. He then told me he has a low sex drive and that any stress kills his libido.

Personally, I am very sexually open, voracious and motivated. I like to feel and express myself passionately during sex, sex with my partner is stress relieving to me. I never tried to alter or conceal this aspect of my personality to him. He on the other hand, is more reserved, often embarrassed of my openness or what he perceives as sexual aggressiveness, especially recently. He is generally very loving and kind, but I am getting to feel like I have moved in with a brother (in a weird inexact sense). I have told him about how important sexual intimacy is to me and how the sudden lack of it is making me feel distanced and stressed. He on the other hand says that his work, life and health stress is making him not feel sexual and that he hopes that it will clear with time. He does have a migraine related condition that has caused health problems and some life disruption. He also says that he thinks I am being selfish about this and not understanding, that bringing it up makes him feel anxiety and makes the problem worse. Also, that if I am so unsatisfied that I could go elsewhere for sex and just not tell him. I find these statements to be very very frustrating and confusing, and I want to build a relationship that is stable with him before I even think about non-monogamy (which I am open to). I am very attracted to him. I know its stressful sometimes in the beginning of relationships, and maybe he is having cold feet issues. He says that he loves me and wants to be with me, and I think he does. But there is definitely a disconnect here, and especially in this area.

I have heard that couples can get more comfortable with time. But I have always had the experience that passion is highest at the onset and that it tends (though not always i hope) to diminish with time. I really like him, and I want to help this work. In other areas, he is loving and friendly, successful at his work and highly intelligent as well as having a normal array of idiosycrasies. But there are times that I feel like maybe we are mismatched or incompatible in these areas and that it won't work no matter what because of our different sexual natures. I have tried adjusting my approach to better suit his needs and I have tried just being totally natural and everything in between but nothing seems to help. I have tried helping out with household tasks and his business to help with his stress.

I was hoping that some redditors might have insight or personal experience that can give me some hope (or difficult truths) in this situation. That sometimes time can make people more comfortable and thus more open leading to increased passion with time.

Any help is appreciated!! Thank you