Definitely don’t force yourself to have sex if you don’t want to!! Maybe you could discuss some alternative ways where he could still feel the intimacy and that you would actually enjoy. Snuggling, perhaps in conjunction with or after he masturbates? See if you can find something that works for both of you. Sex drives also fluctuate, so if this is a recent development it might just be temporary. Neither of you are wrong for feeling the way you feel, if you can’t find something that works for both of you, you may just not be sexually compatible which is nobody’s fault.