I guess it could be welded back

Obtain:

• A micro drill bit. Cheap off AliExpress. A bit more elsewhere.
• A trip to ACE hardware (or hobby craft shop). Get:
  • A thin metal dowel, as thick as the medium thick micro-drill bit. You don't need more than 1-2". Or you can get a couple of thin, stainless steel nails and hack off the ends to size. For this, you'll need good shears or a little saw. Extra credit for using a Dremel.
  • A good, metal-friendly glue or a dual-mix epoxy. I'd ask for advice.

Setup:

• Drill a tiny hole at the center of each side of the loop. Maybe 1/8" or 2-3mm. Standard drill. Protip: the micro-drill bits also fit a Dremel.
• Drill a slightly deeper hole on the body side (assuming it's solid).
• Dry run: test cut a length of metal dowel, enough to join loop and body. Cut to length until both loop and body meet and are flush. The hole shouldn't be too tight. Enough space for glue that comes later.
• The dowel adds structure and distributes stress pressure. Reason they use rebars in cement structures.

Assembly:

• Drizzle a drop of glue into each hole and a little on the dowel. A little more onto surfaces where the broken parts connect.
• Assemble body, dowels stuck into drilled holes on both sides, and loop.
• Wipe excess glue.
• Wrap some tape vertically to hold it tight. Doesn't matter what kind. It's just there to hold things into place.
• Leave overnight to set.
• Grab a beverage and stress-scream into a couch cushion. You are master of the physical universe.

Post-coitus:

• Unwrap tape, admire handiwork, then put back on keychain.
• Tell EVERYONE.
• Post back here with pictures. You've earned it.

Since this is on a keychain, it will be constantly getting pulled. Just gluing it in, or even welding may apply sudden strains and have it snap off at the compromised joints.

This way, it will outlive you and your grandchildren.

Hey looks like it is copper substrate, it could be soldered together!

Bummer, perhaps it can be repaired? By the way, be very careful about sharing photos of keys, it is often quite easy to produce a duplicate key from a photo.

Act like a proper car guy and slap some JB Weld on the bastard

A clamp and some E600 epoxy will make that good as new. Don't give up hope yet, OP.

I totally get it.

I would find a jeweler or metal worker and get it fixed. It might be expensive but apparently it would be worth it to you.

Edit:

Story time- I had a multitool my dad purchased for me before he died. I lost it one day and I was totally bummed. I mean I cried for like a whole day. Over a tool. Anyway I saw one on eBay once by random chance and bought it. When it arrived, it felt like the old one and I realized the object itself wasn’t special, it was what I memories and feelings it reminded me of when I held it. The new one did the same thing, at least close enough. So if repairing is not an option, replacing it might fill the hole.

I found one for you.

https://ebay.us/m/syXXxb

You can reattach that with resin. It looks like thats what its made out of and its coated in somethibg metallic.

Drill, tap, machine screws with loc-tite?

I totally get it. If I like something and use it or have it around a long time I bond with it. Does not matter if it was expensive or cheap but if it was cheap/free I tend to love it more however if it was expensive I tend to be madder at the loss.

I'd braze it but I'm a fucking barbarian.

epoxy time!

Absolutely don't just expoxy it, follow fubarx's tutorial below. Expoxy won't bind sheared metal to metal strong enough to stand up to pocket/keychain abuse. You don't have to go as fancy, but you need non brittle metal to re-connect those shear lines or it'll fall apart the first time you look at it funny.

That's a long time to own a thing. A lot of love goes into it.

I mean...can you kintsugi it?

I think this is the most feels I've seen in this club.

Forza Motorsport 3 specifically hits a sweet spot for me so I totally feel your pain.

I still have the lock box they included in the collector ‘s edition of GTA 4, they don’t make promo swag like they used to.