Sleeping with your liege's wife or daughters out of wedlock should be cause for imprisonment and title revocation/execution if they catch you, and it should be entirely possible that failed targets with traits like Honest will rat you out.
You can already arrest seducers if you caught them though, either directly or indirectly, with your wife, that's for sure, and it happens a lot. I even revoke more than a few titles that way.I think you can also do it with the seducers of your children, I think it happens to me once.
So, frankly, I don't get it when people keep saying you cannot. You can. You cannot every single time and it is fair with me in that regard.
However, there are things that could be slightly altered to be better. For one, I agree with everybody here who is saying that there should be some kind of soft cap on the number of attempts. It could be linked with Traits of the character being seduced, to reflect the nature of the character in question and how much he or she can find it annoying or flattering. Some like to flirt and be seduced, other don't like it so much. It could be linked with Traits. In the first scenario, of loving to be seduced, Traits like Poet, Game Master, Hedonist, Socializer, Gardener, Lustful, Proud, Envious, Brave - if married -, Diligent, Master Seducer, Cynical, Trusting, Patient, Deceitful, Gregarious, could go toward among their respective attributes to improve the number of attempts a character will more easily accept and find acceptable. Going over the threshold should nevertheless trigger an important negative modifier rendering virtually impossible to seduce the target, something a kind to Upset, which should grow if the seducer keep going at it. In the case of the player, when the threshold is met, it should be deactivated entirely, to avoid to be annoyed further. Especially when you try to keep an empire together. In the second scenario, of being annoyed to be seduced, Traits like Chaste, Honest - if married -, Zealous, Wroth, Theologian, Celibate, Temperate, Craven - if married -,Shy, Content, Arbitrary, Paranoid, Just - if married -.
Cruel, Master Schemer, Master Seducer, Impaler, Ambitious, and maybe a few others of which I don't think of should trigger a new event, which is framing the seducer or any character with the Seduction focus. Either a spouse event or a character event, the idea is to be able to create false claims of seduction and to be able to act accordingly. If I am not mistaken, the imprisonment is only available if the seducer do something with the spouse or your children right now. It could be very interesting to see such an event, which will reflect the nature of the seduction focus in the first place. Of course, the event should not trigger for people with good Traits like Just. If it should trigger, it should come with a reasonable chance of getting a bad trait.
That's my two cents anyway.
P.S. : Moreover, now that I think of it, there should be another event triggering if your wife or spouse has lover's pox.It is funny that my character will not notice it one bit and investigate. Thus, there should be a chance to get an event which will lead to investigate further, to follow your wife or whatnot, akin to the one we have currently about babes, when you spend a few coins, then twenty, to know the truth about the father of the child. It could also grant a free divorce since you will have true proofs of adultery. Not only imprisonment.
P.S. 2 : There should be also a negative modifier to your daughters if they are not virgin before marriage- that she has had a babe out of wedlock. Especially when it comes to marry off those daughters for alliances afterwards.
P.S. 3 : I had already post the same message a while ago, but I figure it is still of actuality.