I agree. Though the art and story line are good, it kind of makes me feel yucky inside when one of the main characters can't be faithful and makes light of sleeping around.
If you mean that Shino was unfaithful, he wasn't. Getting raped (he probably didn't struggle because he knew it would be in vain, and he would only get hurt) does not count as cheating! If you get treated badly day after day, you'll get used to it, and simply can't react as strongly as you did before. It's not his fault.
Sluts turn me off so hard. Even if the story itself is good overall, just the fact that a character or 2 are/were sluts really tick me off. Too bad.