Lately i've met a lot of cute women in my city. I meet them in the bar and for some reason, they either have to leave or they have a boyfriend but still want to see me again etc. Some of them give me their number and others don't, they'll just say "Hope we'll meet again soon". Is it a good idea to find them on Facebook and add them or would it be better to just see if we'll meet again by coincidence in the city?

I'm not sure what I signal when I find them and add them on Facebook. It's nice to have the opportunity to contact them again, but on the other hand, if they already have a boyfriend. Would it make any sense?

Thanks in advance and sorry for my poor English.