but that's also "the beginning" of their relationship... Gwen and MJ actually had a bit more in common with each other in the beginning of their relationship than Peter and Gwen did.. but her character evolved. It's not about where they "began" but where they end up.
Not at all. Where they begin is the establishment of the character. The defining of who they are. A character can go off course if the writer isn't very good. But then a good writer can come back in and take the character "back to basics" have them return to their roots. Peter and Gwen's relationship only went off course when Stan left and you had a writer who wasn't interested in the character take over.
but don't you see ... you just described later Gwen as pretty much a perfect match. they were both doing what they thought to be heroic. Peter just wore a mask and costume, gwen did it through activism and protesting. She ironically would get on him about his lack of enthusiasm when essentially he was out every night doing the same thing.. just as a vigilante.
But that doesn't make them
the same person. I've already pointed out how in both doing what they thought was right- it caused a rift between them. And that could have easily continued to spark drama. The differences between Peter and MJ were meaningless. They created nothing. Any rifts between them had already been covered by Peter/Gwen and Peter/Betty Throughout their marriage, MJ was nothing more than a prop. Sexy window dressing or potential hostage.
Black Cat was a serious love interest TO peter... but NOT TO Felicia. that's what sets that relationship apart from being a real "serious" relationship. Black Cat ultimately became the "fun fling" the girl you always had a great time with, was a fun friend, and the passion was hot. but ultimately together you weren't the settle down type. And that stuck with her after their original "relationship" ended. This is why she was so easy to write.. there was no commitments, and no future. It's why they ultimately had him cheat on peter with the Foreigner which prompted him to get back with MJ.
The relationship was also serious to Black Cat. She underwent surgery to remove her "bad luck" powers

to protect Peter, which made her more vulnerable. Yes, in the end, it was decided that they wouldn't last. But it was certainly seriously considered at one point.
I only see 2 ways gwen could have went had she not died...
1) she became carly cooper (who was boring as all hell), who was basically a modern interpretation of gwen anyway, though she'd know who peter was.
or
2) peter never told her his identity.. and the relationship drama and confliction came from that (which to be honest would have gotten stale quick anyway.
Yeah. That's all that the writers saw. That's the problem. There were loads of other things that could've been done. Let's say everything was the same up to ASM #121, but she didn't die. Immediately drama is sparked because she'd be wondering why the f--- the Goblin figured he could use her against Spider-Man.
it why MJ was just a better fit for him imo. Though.. ultimately they wrote her into a hole
MJ was equally boring. That's why they kept removing her. The only drama with MJ was her and Peter getting together after a split. They could never think of what to do with her after she and Peter reconnected. Because again, a modeling/acting career doesn't stand out next to Spidey's life. But Gwen could have gone in more interesting and exciting directions.
and yes.. i'm aware of all the gwen drama, and spidey marriage drama. However.. it doesn't really change the fact that MJ is cemented in history as his #1 love interest.. and the Minnie moue to his mickey, and the Lois Lane to his Clark Kent.. weather people agree with it or not.
Only because of longetivity. not because of good stories. Just as it's really difficult to remember anything Minnie Mouse actually did, it's equally difficult to remember anything from MJ other than "Face it Tiger..." There's nothing unique to the character.
add to that.. with her father's death (whom she blamed spider-man for), and he father's line of work that got him killed. I'm not entirely sure Comic Gwen would have been able to handle Peter's secret life.. or ever agree to it. It's also where Movie Gwen is a bit different than comic
Gwen consistently showed bravery in the face of danger ASM #61,83,92,103,104,108,109,117- She kept saying to Peter that she wanted to face whatever dangers he was dealing with by his side. And she was a scrapper. In the comics she was actually tougher than what was shown in the film. And in MJ's early brushes with danger, she completely freaked. So, if she could be written to be accepting of Peter's secret, Gwen could have even more so.