Code of Honour
Shortly after Encounter at Farpoint and The Naked Now we might be seeing the first expression of guilt over Jack Crusher's death in Code of Honour when Beverly enters Jean-Luc's office to plead with him to get the life-saving vaccine they're after without delay. After the doctor tells the captain that he hasn't had to witness people die of the disease, his reply could be taken professionally, personally, or both.
".... but I have seen my share of death."
And then when Beverly wonders "Where are the calluses we doctors are supposed to grow over our feelings, he gives another view which could express more about his own feelings toward Beverly than the opinion he overtly intends to convey when he says
"Perhaps the good ones never get them."
.... an opinion which Beverly seems to accept as a compliment.
More is implied in Justice, before the sense of guilt is eventually confirmed in Attached during their camp fire dialogue.