Idaho Murder Victim's Ex-Boyfriend Struggling, People Think He's the Killer

The Idaho University murder investigation has been frustrating and heartbreaking for the families of the 4 victims, but it has also taken its toll on the ex-boyfriend of one of the victims, whose life has been upended in suspicion.

Jack DuCoeur dated Kaylee Goncalves for 5 years and called her the love of his life ... this according to his aunt, Brooke Miller, who spoke to the NY Post. Miller believes, although Kaylee and Jack had broken up, they would have eventually married.

Kaylee had broken up with DuCoeur 3 weeks before the murders. Miller says the split was amicable, although she concedes her nephew was sad that the relationship had ended.

DuCoeur was on the radar of cops shortly after the murders, especially because Goncalves and Madison Mogen called him 10 times in the hours before the murders. Cops investigated and cleared DuCoeur, but that didn't remove the specter of suspicion. Miller says "half of America" thinks her nephew may be the culprit.

The Internet has not been kind to DuCoeur, pointing the guilty finger at him.

BTW ... Goncalves' family has supported DuCoeur, saying he was not involved in her death. Miller told the Post ... “We all know, beyond a shadow of a doubt, that there’s no way that Jack would ever do anything like that to anybody.”