Firstly, devarim she’b’leiv einum devarim, so if you manifest kiddushin it is irrelevant what you actually thought.
Secondly, if the couple was “assukin b’oso inyan” (of marriage), the gemara says we assume the money was given for kiddushin and accepted for kiddushin.
It’s also entirely possible that that’s the case only because that was the social convention at the time. As such, the bride and observers would have good reason to think the ring is being given for kiddushin.
Nowadays, however, the social convention is that everyone knows and understands that kiddushin takes place at the actual wedding itself. She knows it, he knows it and anyone observing it knows it. I still fail to see how it could be a kiddushin when neither party wants it to be one and neither party made any verbal declaration that it should be one.
The Wolf