10 POINTS FOR BEST ANSWER?

could be that they're both starting to feel something for you and want you all to themselves. I think they're trying to fight for you, and maybe you best friend wanted to tell you something serious but didn't because he saw how much fun you were having with 'Bob' so he gave up.. I think you should ask the best friend if their was anything he wanted to tell you.. but keep flirting with them and see what happens. Hope I helped! Goodluck!