Tristan Thompson hasn't put a ring on it just yet! Over the holidays, Khloe Kardashian sparked engagement rumors when photos surfaced of her wearing a diamond ring on finger, but a source tells ET that while the two are still going strong, they are not heading down the aisle. «Khloe and Tristan aren’t engaged and it wouldn’t make sense for an engagement to happen right now,» the source says, explaining that with Tristan now playing for the Boston Celtics, Khloe has to go «back and forth between