Hey Arena,
As I've mentioned before, your son and I have/had similarly themed SSRs, first an SSR with both transiting and natal Venuses angular, then followed by an SSR with transiting Saturn angular. And of course, I had/have Neptune closely angular in both my previous Venus-themed and my current Saturn-themed SSR, for better and for worse. Thankfully your son doesn't have Neptune angular in both of his current and previous SSRs. I very much empathise with your son's current depressed and heartbroken situation since I went through similar states of mind last year and earlier this year.
At least, he had someone to reciprocate his feelings of love for some time, and he had talked to his ex-girlfriend (and he is probably able to talk more since his ex is being supportive) to resolve unsolved issues and gain an understanding of his ex's rejection. As for my case, with the "blessings" of Neptune, I've had neither.
But a heartbreak is a heartbreak, and depression is a serious thing—
never to be taken lightly.
Sadly I had to grow out and "get over" of my sadness/depression instead, but I am grateful that I had some support and warm thoughts from some friends that I had already came out to, and of course, the valuable support you guys gave me over here, especially from JSAD, Florence, Steve, Jim, and last but not the least, you yourself.
And then there's the realisation that I've actually never been in an actual relationship last year, that a real relationship would be so much better, and the Jupiter-Neptune hopefulness natural within me that I'll soon get into a relationship so much more worth waiting for, and with much reciprocity and mutual affection. And cuddles.
From Wikipedia's article on
unrequited love:
"Remedies"
Roman poet Ovid in his Remedia Amoris "provides advice on how to overcome inappropriate or unrequited love. The solutions offered include travel, teetotalism, bucolic pursuits, and ironically, avoidance of love poets".
I think this "remedy" goes well for heartbroken people too. And he's a young man, he would sure love travelling and enjoying relaxing, bucolic/rustic pursuits.
It's great you're bringing him to Edinburgh soon; he has his natal Mercury-Jupiter-Pluto angular there, nice for comfort (Jupiter), transformation (Pluto) and maybe even advances in his musical pursuits (Mercury-Jupiter and Jupiter-Pluto). Jim had noted several successful music artists with Mercury angular, pointing that this (their Mercury angularity) probably showed their keen business skills. He also has natal Jupiter setting in his relocated SSR there, and SSR/natal Sun is moderately on the Zenith.
Arena wrote: Wed Sep 06, 2017 3:40 am
If he is willing to stay longer, I will take him with us on vacation in a sunny country in the October school break.
Awesome!
I'm not sure when is his October school break, but if it's on early October, then his demi-SLR on the 1st of that month features a splendid Jupiter-Uranus partile opposition right on the horizon, with Uranus partile rising and Jupiter setting within 1°14'
in mundo.
If sunny country is what you're aiming for (and you're willing to fly to somewhere abroad), how about the middle of Southern France, around Montpellier? His DSLR's Jupiter-Uranus lines pass through there too. And that Jupiter-Uranus is also squaring the MC at the areas around Bari, Italy, Reece, Italy, and also on Split, Croatia, the latter being a beautiful beach destination (but on October, would it still be beach season there?) Another plus is that on these three places, natal Venus rises too, adding for a wonderful and memorable vacation. BTW, I know this sounds very foolish and superstitious, but when I was analysing his charts for these three places in Italy and Croatia, I experienced a very auspicious omen, which through experience I had already learnt to trust very strongly.
His SLR for 14/10 in Edinburgh, though looks bad with Mars sq. MC and Neptune rising, so if his holidays fall during this period instead, it's best to flee to Naples maybe, where his SLR sun's setting there, and his SSR's Venus squaring the MC. In Montpellier, a Venus setting line is present this time, but Mars is setting too, not far away.
I wish your son a speedy recovery from his depression—nothing bad lasts forever, and hope, along the love from your loved ones, are strong forces that keep life running.
And then there's the realisation that I've actually never been in an actual relationship last year, that a real relationship would be so much better, and the Jupiter-Neptune hopefulness natural within me that I'll soon get into a relationship so much more worth waiting for, and with much reciprocity and mutual affection. And cuddles. 
I got transiting Saturn ecliptically within 6º from his SSR MC too.