Troubled sex drive...πŸ˜”

I've been with my SO for about 8 months now (him 23, me 20) and lately I really haven't wanted to have sex. I know he's frustrated with it, and so am I because I feel like I'm letting him down. Sometimes when he kind of starts doing things I'll just go with it, but last time I ended up getting so upset and started crying. He felt terrible and said if I don't want to, I just need to tell him. A little info... He's never made me orgasm, we've enjoyed sex a lot in the past, we never had any fights until about now... Any advice on how to increase my sex drive or any ideas on what could be making me feel this way? And help would be greatly appreciated, I just want to want to have sex again and feel good about itπŸ™