I'm not sure what bondage has to do with anything.
It sounds to me like he is trying to make you happy, and maybe he likes the thought of owning you.
Do some more research, and decide what significance collars have to you. Write down what you believe they represent since you'll get as many different answers to the same question as a dog has fleas. Not all collars have to be "serious." Some people give 3 collars: a blue collar of consideration (like a promise ring), a red or black training collar (like an engagement ring), and a metal slave collar (like a wedding ring).
My views on collars have changed considerably over the last 2 years. In the relationship I'm in now, Daddy doesn't believe in collaring submissives because, to him, collars denote owned property. Since submissives haven't given over total control, they aren't property. He will only collar a slave, so guess what I'm going to be? *smiles* Daddy and I have some slight differences in opinion, mostly that I like the idea of 3 collars whereas he prefers to just do it once. He also had to convince me that I'm slave material since I was told by others that I'm barely submissive. *ggls*
When Daddy teaches others in the lifestyle, he tells them his views on collars, but he also tells them that it's whatever it means to them. He thinks it's endearing when D/s couples want a symbol of committment, not offensive. He just wants people to make sure they understand what it means to the both of them so that there's no confusion.