"I'm allergic to ..." Yes, I know.

"I don't like onions in my sandwiches ... " Yes, I know.

I don't get to spend a lot of time with my guy, so even though we've known each other for some time, we don't really know each other. I'm really detailed oriented, so when he tells me a preference, I lock it in. Next time we meet, he'll tell me about that preference, and I often reply with "Yes, I know" or "Yes, you've told me already :) " because I want him to know that I listen and pay attention when he tells me these things. However, it feels very shrew-like, a bit nagging and I think it may make him feel foolish for repeating himself. I don't ever want him to feel that.

What are some alternatives and actions I can substitute with while still letting him know that I do listen and remember the things he has said?