IMO they are quite similar, its just in SR he is going to see if Krypton is still there or if he can help any potential survivors. In 'For Tomorrow' he leaves loved one's in the dark as well about his actions, its just that some manage to find out of their own accord.
Perhaps I should have been more clear. Not his motivation for helping others, but his motivation in his actions toward Lois, the woman he loves.
In "For Tomorrow" he is going to save Lois and a million other people he feels he has a chance of saving. He is going to save the woman he loves, the most important person in his life, no one else is as important to him as she is.
In SR, he ditches Lois without a word. THe woman who is the most important person in his life does not rate a goodbye. Can she really be that important? Can he really love her and have her best interests at heart?
These situations seem similar in one respect, but COMPLETELY different in reference to Lois.
Yes, WW in particular thinks he will make it worse and tries to stop him in numerous ways.
She and Kal haven't had the best relationship over the past few years have they?
As i say above, his motivations are basically the same, in SR he goes to Krypton to help any potential survivors or see if it is still there, or even if his parents are still alive and in need of help, in 'For Tomorrow' he goes to find Lois and the other 1 million people that dissappeared during 'The Vanishing.' His motivation in both scenarios is to find loved one's and to try and help people that my be in need.
But in "For Tomorrow" he's not turning his back on the woman he loves, the most important person in his life, the woman he's having a sexual relationship with.
That makes all the difference in the world. In "FOr Tomorrow" it wouldn't matter if it was a million people or jus Lois, he would still go to try and save Lois, that's what love is about, you care for them more than anyone else. Clearly, in SR, Superma is not caring for Lois more than anyone else, otherwise he would have said goodbye and explained what he was doing.