<human>: Can you provide a brief rundown of the text in within 3 sentences?

Background: We're together for 3 years, have been FWBs for a year before our relationship started, live together for 2 years

I'm having a problem with telling her that things she does for me are sometimes "bad". I guess its best shown in examples: So she is a natural person, she basically never uses makeup, which I'm totally fine with. Once I told her that maybe she could try it, because I like experimenting. Now I guess she was bad at it, which is kinda obvious since she has no experience. But I wasn't able to tell her that it was not so great and how I would like it better, because I know that she stepped out of her comfort zone doing that and she did that for me. If I tell her that it was not so good, even if I am doing it ultra careful and sweet, I feel like a rude, ungrateful asshole and fear that she will never step our of her comfort zone again.
Now thats just one example, but as I said, since I like experimenting theres lots of those situations, they're tiny, but they add up.

Am I overreacting because of how much "Told my SO that xyz and she didnt react very well" threads I've seen? Do you have any advice on how to deal with such things?
<bot>: when she does sth for me but isn't good at it, I can't tell her that because I fear she'll be mad