Goodness. I know exactly what you mean. My "pup" is now 18 months and just drops everything when there's another dog involved which gets embarrassing when you're out on the trail. He thinks all dogs are put on earth to play with him. Not every dog appreciates this! Everyone has really great advice but I just wanted to throw one more thing out there.
At the suggestion of a trainer, I take my dog to the dog park where it's acceptable to have your dog play with other dogs

and when they're playing with another dog, when you see a break in the action if even for the slightest moment, call them to you (assuming you've already trained them with a recall command) and treat with something yummy (ours loves hot dogs), lavishly praise, then give them the release command and allow them to go back and play. Repeat. Repeat. Repeat. This teaches your dog that it doesn't mean it's time to go or that they have to stop playing every time they're recalled. It's also teaching them to listen to you when they're in the throws of puppy playtime passion.
I gotta tell you, I'm seeing good improvement when we're out on the trail and he bee-lines it towards another dog. He's not 100%, but he'll stop and come running back. And if the owner is OK with Loki approaching, I'll give him the release command.
Good luck! I also think that's just how puppys are!