I'm sorry but this is worse than paying a kid to come to your school, or having boosters throw parties for recruits. A person was made up, killed off, squeezed for publicity, and lied about. That is sick... there are only two realistic conclusions I think that you can come to...
1.) This was all to try and raise Manti's profile. I think this is what a lot of people will conclude, but I think it's otherwise.
2. (My theory) I'll preface this by saying the only condemnation I am laying on Teo is the hoax I think he created. That being said, I think the guy portraying his "gf" was either his boyfriend or associated with a boyfriend, and Teo was afraid to come out. So instead, he made up a gf for public persona. His family knew of his lifestyle, so he quickly let them know he was faking the relationship. When he felt significant time had passed, and knowing as a future star people would start looking for his "significant other" the plan was formed to "kill her off". That would keep his invented image intact, and give him space to stay away from the media when it comes to dating. The story then took off, more then expected, and the hole hot bigger every time he opened his mouth...