I'm not so sure that it's because he feels there's nothing he can do so much as he worries about imposing in the lives of others. In the case of Dan Scardino, what could he do? Lois was justified in looking for a new boyfriend since he was constantly running off and he refused to be truthful with her about why that was. If he could have been truthful, or at least *there* for Lois she never would have given Dan the time of day.
When it comes to Dr. Deter, that was just poor writing on the show's part. That entire clone/amnesia arc was ghastly and out-of-character for him (IMHO). Even if he did believe that Lois suddenly loved Lex why was he willing to let Lex just drive away with her? He was an escaped convict! That's not fatalism, that's inconsistent writing. Same thing with Dr. Deter. Clark should have insisted that she get a second opinion.
(Of course, it really the fault of TPTB on the show, because they wanted to ratchet up the tension to keep viewers.)
Funnily enough, they completely lost me instead.
