Part-time Girlfriend?

Last week, I wrote a personal message on msn. The personal message is " I'm looking for a long relationship."
Few days later, a guy asked me: "are you looking for a relationship?"
I said: "yes, why?"
" How about we have a relationship? I'm looking for a part-time girlfriend." he said...
" What do you mean PART-time girlfriend?" I asked.

Then, he told me that part-time girlfriend is like.......
1. Don't have real relationship. ( we not admit that we are couple)
2. He only will date me when he's free. (mean that I have to follow his schedule?)
3. Can look for another relationship. (This mean I cannot angry if i see him date with others?)

He told me it will be fun and ask me to try...
I said I will think about it.

What I really think about it is.... Part-time girlfriend really sounds like a prostitute. No....! should be more worst than a prostitute because prostitute still got money to earn, but a part-time girlfriend earn nothing.

PS: I won't make myself so cheapskate la.....