↳ Mary struggles to accept her strange new reality, riddled with grief as she mourns the babies she lost.
Sam: We're right here, mom.
Mary: I know. In my head. But I'm still mourning them as I knew them... Just feels like yesterday, we were together in heaven, and now...I'm here, and John is gone, and they're gone. And every moment I spend with you reminds me every moment I lost with them.
i sometimes make myself sad by thinking about dean winchester and sunsets and what they really mean for him.
let me explain.
in 2x07 (oh so long ago), dean mentions that he enjoys sunsets as he makes his "confession" for diana and pete.
a decade later, in 11x11:
when you first watch this scene, it just feels sad because of how far dean has come and the crushing weight that constantly rests on his shoulders, preventing him from enjoying something as simple as a sunset. but i think there's more here than just that.
the conversation that follows after mildred's question is about retirement, about ending life on the road (mildred was also a traveller), and also about following your heart, going where it tells you to go.
now, to show how this is destiel-coded (because everything about dean winchester is ultimately destiel-coded).
dean calls cas "sunshine" a few times throughout the show.
7x21
12x03
and remember dean's retirement plans in 13x23?
yup. going to a place where there is a LOT of sunshine. specifically with cas. who is dean's sunshine, his source of light in the absence of chuck/god. given that angels are regularly associated with light and lamps throughout the show, it's no great surprise that dean thinks of cas as the sun, the greatest source of light out of all of them.
so, cas is dean's sunshine, and dean winchester enjoys sunsets. why does he enjoy sunsets? because they are the last part of the day he can properly enjoy before having to think about and deal with the things that "go bump in the night." or, according to the show's meta, it's the final moments of the time he can enjoy being in the sun (with cas).
why does he stop having time to enjoy sunsets? because in season 11 the darkness becomes suddenly becomes manifest as character who is pursuing dean, confusing and scaring him by claiming that they are bound together by destiny and that they are fated to be together.
now for a bit of a tangent, which will connect back to this.
think back to the end of 2x18, only 11 episodes after dean first says he enjoys sunsets.
the winchesters walking off into the sunset together. but then -
the curtain is lifted, so to speak, and reality is revealed. because sunsets, being able to enjoy sunsets, is a bit of a fantasy for dean. they're something he can only fully appreciate if he has a "normal" life where he isn't repeatedly saving the world.
the show seems to revisit this idea in 11x23 when they show the darkness/amara trying to kill the sun (i.e. dean's sunshine, who is cas, who is, as amara has realised by this point, her primary rival for dean's romantic interest). in other words, they are taking dean's hopes and revealing them to be an unattainable fantasy.
as always since cas first walked into that barn, throughout season 11 there are strong indicators of cas and dean's very-much non-platonic feelings for each other, which is why the moment with mildred is so important. it reminds dean, in a time when he is facing the biggest threat he has encountered yet, that he can still dream of and hope for retirement. that he can still enjoy what he has with cas. that he can follow his heart (when mildred says that, we know that he's not thinking of amara).
yet once again in the finale, the show crushes those possibilities. dean is ready to give his life to stop amara (i.e. save the sun i.e. save cas), but once he succeeds, he still isn't able to enjoy the sunshine he has saved because sam has been kidnapped by the british men of letters and a whole new cycle of figuring out how to overcome this next obstacle begins.
so while 2x07 is well before dean meets cas, maybe the reason the show (accidently? intentionally?) revisits this character trait of dean's is because sunsets, the moments of passage from day to night, are, for dean, a balance. between hunting the things that go bump in the night, saving the world again and again, and having cas alongside him.
sunsets are dean's compromise between those two parts of his life, until he can retire. and then he can go to a beach somewhere and have all the sunshine he wants.
but maybe dean is tired of having to make this compromise, which is why he tells sam about his retirement plans in 13x23. because in the first episode of that same season, cas died and they burned his vessel.
and they did it at sunset. which is supposed to be dean's symbol for the compromise he makes to have cas in his life. and it might be here, in this moment, that dean realised a comprise wasn't enough.
going back to his confession in 2x07:
in addition to sunsets, he ALSO says that he enjoys long walks on beaches. so as 13x23 indicates, dean is done with compromises/sunsets. he truly wants to retire because he believes that, with jack's help, he can make the world safe. he believes he's earned his sunshine with cas. and retiring from hunting is the only way that the people he cares about can be safe.
anyway, that turned out to be a bit longer than i intended. i just think these connections between dean and sunsets and cas are very beautiful and sad, and one of the many accidental ways the show shows us how much they care about each other.