You're taking to specific examples now. But I'll try to elaborate each;
In regards to the Relationship example; If you have two players, from which one drops off the radar, and they have a relationship going, you don't have to Retcon anything. The player is gone, therefore you can have your character simply say 'I've not seen him since (insert time here).' Take it Icly. The Character vanished, therefore the love has been abandoned, therefore the other character can continue playing from the relationship having ended up broken because the other character suddenly dissappeared over night. Keeps everyones story going with no Retcon involved.
As for the leveling to 50, changing names bit;
Those are game mechanics. Askier has done a wonderful example of how you can switch things up, and moreso how your ingame presentation =/= your character. Your overhead name can be 'James Castiel', and  you can still be playing 'Victor Harness', by switching up the appearance.
Also, it is 'not' obnoxious to want people to play by the same rules. What is obnoxious is assuming everyone has to take heed and care to your personal 'feelings', because you don't 'like your character anymore'.
You restarting your character in order to have a better experience affects exactly one person. Yourself. You're dealing with your own problem.
Retconning because you don't want to re-level/use the same base model/don't want to use fantasia creates a problem for various people, case in point 'everyone' who's played with you so far. That is the definition of Egoism. Before I have to deal with my problem, I'd rather just ignore it/retcon it and make it a problem for everyone else.
This has nothing to do with being inconsiderate towards other players. Infact, being against Retcon means the opposite. You care for the roleplay you do, and others have, and would rather sacrifice your own character then to disrupt the RP environment/flow/story-telling because you right now 'just don't feel your character'.
The only instance in which Retcon should be, in any way justified is if the roleplay was based on faulty information to begin with, or any godmodding/metagaming/ other RP breaking things have been done.
So to make it short:
Making a new character makes it a problem for 'one' person: You. You feel your chars not up to par, you make a new one.
Retconning makes it a problem for far more people. Because you don't want to go through the work, everyone elses story has to suffer.
Also, I think it's important to define Retcon again. Retcon is about ignoring/changing aspects of your character/the story. It is not having your character move on from a broken storyline that's not going anywhere.
In regards to the Relationship example; If you have two players, from which one drops off the radar, and they have a relationship going, you don't have to Retcon anything. The player is gone, therefore you can have your character simply say 'I've not seen him since (insert time here).' Take it Icly. The Character vanished, therefore the love has been abandoned, therefore the other character can continue playing from the relationship having ended up broken because the other character suddenly dissappeared over night. Keeps everyones story going with no Retcon involved.
As for the leveling to 50, changing names bit;
Those are game mechanics. Askier has done a wonderful example of how you can switch things up, and moreso how your ingame presentation =/= your character. Your overhead name can be 'James Castiel', and  you can still be playing 'Victor Harness', by switching up the appearance.
Also, it is 'not' obnoxious to want people to play by the same rules. What is obnoxious is assuming everyone has to take heed and care to your personal 'feelings', because you don't 'like your character anymore'.
You restarting your character in order to have a better experience affects exactly one person. Yourself. You're dealing with your own problem.
Retconning because you don't want to re-level/use the same base model/don't want to use fantasia creates a problem for various people, case in point 'everyone' who's played with you so far. That is the definition of Egoism. Before I have to deal with my problem, I'd rather just ignore it/retcon it and make it a problem for everyone else.
This has nothing to do with being inconsiderate towards other players. Infact, being against Retcon means the opposite. You care for the roleplay you do, and others have, and would rather sacrifice your own character then to disrupt the RP environment/flow/story-telling because you right now 'just don't feel your character'.
The only instance in which Retcon should be, in any way justified is if the roleplay was based on faulty information to begin with, or any godmodding/metagaming/ other RP breaking things have been done.
So to make it short:
Making a new character makes it a problem for 'one' person: You. You feel your chars not up to par, you make a new one.
Retconning makes it a problem for far more people. Because you don't want to go through the work, everyone elses story has to suffer.
Also, I think it's important to define Retcon again. Retcon is about ignoring/changing aspects of your character/the story. It is not having your character move on from a broken storyline that's not going anywhere.