She's got her own career, her own capacity for time travel, her own ability to deal with problems, and in general a life where the Doctor is pivotal but not everything. Great! Then Moffat gives her a line about how having the Doctor not recognize her will be worse than dying. *headdesk*
This is where the characters' relationship really matters to the interpretation.
If someone were to say something similar about a friend or acquaintance they are attracted to, then, yes, it's a little over the top.
OTOH, if the person who is saying this has been in a long-term partnership (which is what the storyline is leading us to assume), then not being recognized, even when there is a reason that you can anticipate, is agony. To draw a real world corollary - River's situation is like a spouse of someone with worsening dementia. He has a glimmer of recognition that she was once important to him, but can't say why; she suspects someday there won't be even that.
no subject
This is where the characters' relationship really matters to the interpretation.
If someone were to say something similar about a friend or acquaintance they are attracted to, then, yes, it's a little over the top.
OTOH, if the person who is saying this has been in a long-term partnership (which is what the storyline is leading us to assume), then not being recognized, even when there is a reason that you can anticipate, is agony. To draw a real world corollary - River's situation is like a spouse of someone with worsening dementia. He has a glimmer of recognition that she was once important to him, but can't say why; she suspects someday there won't be even that.