I also disagree. I found some places to be more "inherently romantic" than others. Paris and Venice are good examples.

To each is own. Paris is beautiful and inspiring but I didn't find it anymore romantic than NYC, Rome, Barcelona, Sydney, or even Tokyo. I don't find the energy of a big city romantic at all (I will say that I do find Stockholm and Venice very romantic though).

When I suggested Paris, I was thinking more about art, architecture, history. culture, food, and wine rather than sucking face in front of some tourist trap.

I am in Paris at least 3 months every year if you combine the time of my various trips. It is perfect for a broken heart. You cannot be sad there, it has distractions galore, it is easy to meet others and easy to be alone. The only three hostels worth considering are, in order:
The MIJE absolute top choice for clean, safe, well located one block from the Ile St. Louis and the 1 Line. Next St. Christophers, very happening and pretty right on the canal but not a great location at all. Oops, located on the border of the 5th and 13th gets mixed reviews but no bad ones. The other Paris hostels are awful.

I think Barcelona is a better bet. Younger, less pretentious and less expensive. But still all the diversions that make traveling solo enjoyable and fulfilling.
Why a hostel? Stay in an apartment and have space and comfort. A little self-pampering is in order! Pick the location based on your interests (and proximity to the Metro, which is less convenient than in Paris) an you're on your way. I recommend the El Born area.

I disagree with the recommendation to stay in Montparnesse. I was in Paris in May and stayed in that area and hated it. I could not wait to get on the metro and go anywhere else.

I was in a similar situation when I went by myself. It can be a hard city. In all my travels I have never stumbled into proposals that way I did in Paris. But that doesn't mean you can't have fun. My only recommendation would be to tell your friend to not let being there by themselves stop them from doing anything that they want to do. One of my best memories is sipping champagne at the top of the Eiffel Tower at night and than sitting in the Trocadero, eating dinner while watching the lights twinkle. Typically romantic moments but I really didn't mind being there by myself because the moments were just so special. And that is what counts.

We go to Paris every six months and it's perfect for anyone. We enjoy staying in the Latin Quarter, we love Rue Mouffatard. Paris is a great place for anyone, I haven't noticed kissing everywhere. Comfort Hotel Mouffatard is a really nice place to stay.

Any vacation, any where is good for the heart. By the time we finish hashing this out, he'll have moved on and had 3 kids. Hope he makes it to Paris anyway.

Sorry, can't help you with a hostel.

Puttakka,

I love that you recommended Paris to him. I have been to Paris before... and am currently thinking of going again. Solo. I find it to be one of the most enchanting places in the world, lovely and inspiring if you go with your loved one(s), and just as lovely and inspiring if you go with your own self. I could say I'm in the same boat as him, at a pretty down time in my life, and the only place I see myself wandering around alone without feeling miserable is Paris. ( London may qualify for me as well). The city, the art, the architecture, the pulse - all are wonderful experiences to have on one's own, in my opinion. In fact, a solo trip to a city like Paris might be exactly what he needs to do some soul searching. And that image of Paris - couples making out etc... - is one that comes from movies and romance novels. I didn't see it there any more than I do in any other cosmopolitan city. Good luck to your friend.

When you have a broken heart, every place your beloved isn't, is awful. Paris is worse, not because it's particularly more romantic, in reality. It's just the IDEA of Paris that's so romantic. That's the Paris brand, for goodness sakes. Let's face it, when you're madly in love, Podunk is heaven. When you have a broken heart, the universe is hell. Nevertheless, Paris is as good a place as any to be miserable. The upside: someone new might come along.

So what has happened? Has your friend travelled yet??