Poor little Scotty,
Fell off his potty
When he was a two-year-old laddie,
And that's why he ran out on Maddie.
Later writers added more of the same, not just by having Scott become a repeat offender by cheating on Jean and retconning his love for Jean into a symptom of emotional immaturity, but also in their destruction (I refuse to use the pompous euphemism "deconstruction") of the character of his surrogate father Charles Xavier (Deadly Genesis etc.). But it is still to my mind simply idiotic to blame Madelyne for marrying Scott because she did not anticipate the way Scott's character would be altered beyond recognition four years readers' time later.
When looking pre-1986 Scott, I think pre-OMD Spider-Man actually makes a better comparison than Captain America, as Scott Summers and Peter Parker are both traumatized by loss and weighed down by responsibility. And so from a pre-1986 perspective the Pryor-Summers matchup was no more doomed from the start because of Scott's feelings about losing Jean than the Watson-Parker one was by Peter's lingering feelings over losing Gwen Stacy.
What's the problem with declaring Scott's abandonment as OOC, as a serious deviation from the established characterization of the preceding 23 years? It is certainly not inadmissible just because another two decades later Scott did something equally outrageous and at variance with his established characterization, sorry.
Also, I would dispute that Scott had difficulty imagining himself outside the X-Men leadership position. Ever since UXM #138, living outside the X-Men was his default mode, and it was not his inner compulsion but exterior forces that kept bringing him back (stumbling upon Magneto's island lair in time for #150, getting involved with battles in the Shi'ar galaxy not least thanks to being Corsair's son, being kidnapped by the Beyonder for the first Secret War, being targeted by Loki for X-Men/Alpha Flight, being summoned by Moira MacTaggert to Westchester in UXM #199). He only started displaying his "the X-Men need me" attitude in UXM #201, which not so coincidentally appeared the same month that Jean Grey returned from the dead. But to claim that he could not function in anything other then the position of leader of the X-Men is projecting NuScott back to the past. Scott was shown to be quite happy working as a fisherman under Aleytis Forrester and by all in-story evidence was perfectly happy as Madelyne's husband and colleague at his grandparents' airline. (Let's not forget that after his wedding he was in that position with just two short interruptions (for MSHSW and XM/AF) for close on to a year, story-time (Madelyne's pregnancy only becoming known in XM/AF).