I visited my male friend (he is a native American) in the USA on a tourist visa(B1/B2) twice in 2009.In 2010 I applied for a student visa twice and was denied.My male friend's family was my sponsor.I applied one more time for a tourist visa in 2010(to visit a friend of mine) but was denied.I would like to visit the USA again in the future and see my friend and some other buddies I have there.My question is:Should I ask my male friend to send me an invitation letter (like I did before) to apply for a visa or choose another friend of mine to do it? I am afraid consuls thought my male friend is my boyfriend.:( Maybe if I ask a female friend of mine to send me an invitation letter to the USA it can increase my chances to get a visa? I am from Russia. Thank you ahead!