Thank you very much for the response captaincay. Though below are my follow up questions.

Q1: 1. Is it more difficult applying tourist visa if your boyfriend who is sponsoring your visit haven't been visited you first?
- Is emails and skype communication not enough to prove that your are in a relationship?

Q2: Is it a big question if you have a relative living in UK and not the one sponsoring your visit?
- Is it okay not to mention in the application form that you have a relative living in UK?

I really appreciated your time for answering my questions.