hey so you know how captain spaceboy's name (obviously) has 'captain' in front of it? and how space ex-boyfriend doesn't? that's because he neglected and effectively abandoned his title of the captain whilst dating sweetheart and when refusing to leave his bed after their breakup. he still values the connection to sweetheart more than he does to his crew; he isn't the captain when he's ex-boyfriend, because he doesn't care about leading the crew. the only thing on his mind is sweetheart. like how when he becomes space (ex)husband, that too replaces the 'captain' and 'boy' parts. he's not a boy with sweetheart, he's a man; a suitor. and he's not a captain. he refuses to be, because he has to put her first, even when they've left each other. stranded on a mountain and slowly freezing to death, spaceboy doesn't care about the pirates, or his father, or his own identity. he cares about sweetheart separating from him again, and the heartache he felt as a result.
sweetheart's impact on him in canon is so huge but i don't think we as a fandom tend to truly understand that. he changes his name for her, has multiple identity crises, would've been ready to die if it hadn't been for omori & co's intervention. spaceboy had his faults just as sweetheart did, but he also had it rough with her. sweetheart expects a partner to give up everything for her and yet is unwilling to sacrifice the same. just look at "sweetheart is for sharing" and rococo's entire thing! she's not something 'girlfriend', something 'wife'. she's always duchess sweetheart. sweetheart is able to prioritise herself to the point where it becomes a problem. she doesn't care about spaceboy because she deserves the best, and she doesn't believe that's him. spaceboy sacrifices it all, and they always end up falling out. and he always ends up more depressed each time.
'captain' is more than just a position. it's spaceboy when he's secure and confident in himself. it's spaceboy when he has friends. it's spaceboy when he isn't destroying himself with a toxic relationship that's only going to hurt him.
his father, captain pinkbeard, knows that, and wants to keep things that way. i'm so glad spaceboy has a (somewhat) secure support structure, because boy does he need one.