Click here for part one. **Warning Of Spoilers For Lois and Clark: The New Adventures Of Superman (1993-1997), and several Superman comics!
There are two main schools of thought on Superman having romantic relationships. One suggests that he works best as a single man and the other suggests that he should stay married to Lois Lane.
While one could say part of his success has to do with being in a romantic triangle with himself (as both Superman and Clark) and Lois Lane, this is also partly a falsehood. Yes, this angle probably helped attract many readers, but it presumably caused a lot of frustration due to all the teases at marriage. For example, various stories featured in the series Superman’s Girl Friend Lois Lane (1958-1974), including the story “When Lois Lane Hated Superman” from issue 39 (Feb. 1963). Another example being Clark’s marriage to a fake Lois in Lois And Clark: The New Adventures Of Superman. According to an article by Russ Dimino on Kryptonsite, this tease supposedly frustrated fans of that show. However, it is true that for adventures that take place in Superman’s early years, the romantic triangle works.
Yet, when one thinks about marriage, one should consider how long it took to get there, not only in terms of years but decades (to be specific it took 58 years before the marriage happened in Superman: The Wedding Album , and the engagement, which happened in Superman #50 , for various reasons took 6 years). Then one should consider how even before the main Superman stories added marriage, there existed married Superman stories. Said stories star the original Earth-Two Clark Kent and Lois Lane as Mr & Mrs. Superman (Action Comics #484  and Superman Family #211 ). These stories show that Clark and Lois could still work and be successful even without the triangle.
In conclusion, I would say the later set the story is in Superman’s history, the more development he should have with Lois. Meaning if a writer has a story to tell involving the triangle, they can always do a previously unseen tale from their past.