Humphrey had exactly the same problem with a young dog in the neighbourhood. We had hoped we could walk the dogs together and met up a couple of times but the other dog just wouldn't leave Humphrey's ears alone, he was literally hanging off them, and in the end I had to intervene, it was getting on my nerves, Humphrey clearly had difficulty manouvering and defending himself while the other dog was attached and although my neighbour seem to think they were just playing, I suspected it was more bullying.
The last time we tried to meet up afew months ago, Humphrey started to snarl and growl at thenother dog as soon as he saw him, so I was clearly right in thinking he'd not been happy either.
None of the other dogs that he plays well with have ever attempted to go for his ears so I do suspect that its not part of well mannered play but is probably a bit more aggresive. We sometimes meet the neighbour when we're out but all attempts to get them to accept each other has failed and we now have no option but to give them a wide berth.