Do utilitarians know how to do utilitarianism properly?

I've been browsing this board for a while now I have a concern. I am utilitarian and I know that utilitarianism is a theory of ethics. It isn't a proper moral theory on its own because it isn't a solution to the is-ought gap.<br><br>In order to do utilitarianism properly one must do the following: ***Determine what is***, ***determine what one ought to do***, and ***determine what is the right strategy, or tactics to accomplish the goal***. In utilitarianism that goal is to create the maximum amount of happiness. <br><br>Example for the problem:<br>I utilitarian. I think that, generally, we ought to be kind to people.<br>Then I go to my friend's house and am greeted by his/hers wife/husband. This person is my friend. I like this person. I want this person to be happy.<br>I then learn that my friend cheated on their spouse. This person is my friend. I like this person. I want this person to be happy.<br><br>Who should I tell first? Sometimes the best course of action is to tell the spouse, but sometimes the best strategy is to tell the cheating spouse. It really depends on the situation. In utilitarianism we don't care about if the person is good or bad. All we care about is maximizing happiness. In this case, sometimes it is best to tell the spouse. But sometimes the best course of action is to tell the cheating spouse first.<br><br>My point is, that utilitarianism is not a theory of knowledge. In the last paragraph I argued that I believe sometimes we should tell the spouse, but sometimes we should tell the cheating spouse. Can I truly say I am correct? I don't know.<br>We can easily say we ought to do this. But we can't do it the way we should because nobody knows for sure how to do the best possible thing, at least in a practical sense.<br><br>&#x200B;