Common romance problem: The person I loved years ago has changed; is our relationship still possible?
This problem is interesting. It is more interesting if the characters take responsibility for their changes. Sometimes, the characters regret their own mutability. Sometimes, they feel a sense of inevitability. But they nearly always become more interesting if they desire to move forward rather than back--there's no point wallowing in the past; maybe, we can remake the future.
In Dry Heat, the main character struggles with guilt since he believes he caused another person to change: I'm responsible for Tatsuhiko's punk behavior. He also has to accept that the person he loves is no longer the image he carries in his head. U Don't Know Me (see above) opens with a main character questioning what leads people to grow apart--are the physical changes (my best friend is now several centimeters taller than me) a reflection of the emotional changes?
A variation on this problem is when a character realizes that the type he or she always fell for in the past is not, in fact, the best type for that character to grow old with. Black Sun falls into this category as does What Did You Eat Yesterday?
Common romance problem: I don't think this relationship will last.
Maybe it will. Maybe it won't. By itself, the yes/no possibility is less like Schrodinger's cat and more like a T/F question. Once it is over, it is over. Besides, if one is watching particularly irritating television, it's more or less a given that the relationship won't last (see Ross & Rachel).
What makes this problem more interesting is if the characters tackle the problem from within their personal philosophies/self-concepts. In Apple & Honey: His Rose-Colored Life, Komano questions Natsuki's tendency to carry the justifiable fears about the relationship on his shoulders alone; Komano's objection is rooted in his belief "I can decide my own future. Don't anticipate trouble for me."
A fascinating variation on the "I don't think this relationship will last" problem is "How much of my self will remain if the relationship does last?" One of the most captivating scenes in Finder occurs when Akihito--faced with a choice between Asami's apartment key and his, Akihito's, camera--chooses the camera. It isn't that he isn't enthralled by Asami; rather, like Jane Eyre towards Rochester, he recognizes his enthrallment and thinks, "If I don't struggle against this, I'll end up disappearing; I won't be anybody anymore."
Common problem: "My partner cannot be trusted based on past behavior."
This problem has almost no self-life. Either the partner can be trusted or not. End of story. (And solving the problem based on luuuvv makes the characters look stupid. If their sense of personal worth is so damaged that they won't take previous bad behaviors as a warning, they aren't worth investing in as characters.)
Yaoi specifically does provide a possible variation on this problem--but only if the reader concentrates exclusively on the narrator's arc: Is my self-doubt causing the lack of trust rather than someone else's behavior? Wataru of Only the Ring Finger Knows tackles this question by deciding, Yes, but Kazuki needs to stop keeping stuff from me, and it is my responsibility to tell him so. He takes far longer to figure out that Masanobu cannot be trusted based on Masanobu's past behavior, which is--as one would expect with this trope--somewhat more irritating.
Common problem: "How do I prevent an external bad thing from happening to us?"
|The internal identity arc is helped|
|if characters take responsibility|
|for the externals they put into motion.|
Blue Morning is a great example of a storyline where both Katsuragi and Akihito are trying to prevent bad things from happening or, rather, one bad thing from happening: the disintegration of the Kuze family (and its attendant responsibilities). But how they do it--and how the how impacts their relationship and their views of themselves--is radically more important than doing it, as is often the case in politics!
Summing up, internal issues such as confusion or disillusionment or doubt help any arc. But states of mind are often not enough to keep an arc going. Writers do much better if the state of mind goes back to a fundamental need or want--the character's place or identity in the world, not just the character's temporary feelings.
See Votaries for this same post with non-yaoi examples . . .