People who hate SOTR/Lenore Dove like to very much misinterpret the graffiti secret.
No, the point of LD's secret isn't the fact that she did anti-capitol/anti-games graffiti. The point isn't even that she didn't tell Haymitch (which btw I really hope I shouldn't have to explain why people keep antifascist activity a secret from everyone, even those they love and trust most).
The point is that Maysilee knew but didn't tell anyone and kept LD's rebellious activities private, even from her boyfriend who agrees with her.
Haymitch isn't surprised when he discovers LD's spraypaint after her death. Because he knows it's a Lenore Dove thing to do. The reason LD didn't tell him is because she wants to keep it private, not because she doesn't trust him, not because it's meant to be a big reveal. No it's because you don't fucking tell ANYONE about stuff like that when you live in a government like that, even if you trust the person entirely. There's ears everywhere in D12, LD not telling him has nothing to do with her trust in him, it has to do with the politics of what she did. Again, I really hope I don't have to explain why someone might keep their anti-dictatorship activities secret, even when it comes to someone they love and who agrees with their beliefs.
The point of Maysilee knowing LD's secret never had anything to do with Maysilee knowing LD's secret when Haymitch doesn't, really, it has to do with Maysilee SEEING HER MAKING THE GRAFFITI and still not telling anyone, even Haymitch, about it, because despite Maysilee and LD not being friendly, they still agree with one another politically. Regardless of how LD sees her as a person, Maysilee still respects LD and knows that if the secret got out, even to someone who loves her and shares her views, she would still be at risk. That's all.