Lamar Odom and Sabrina Parr are apparently BACK ON -- just one week after Parr announced they had broken up so Lamar could focus on his personal issues.

The two hopped on a plane early Thursday morning for a quick romantic getaway. Unclear where they were headed, but once they touched down, the two posed or a kissy face photo, seemingly to show social media they're back together and happy.

Parr says they are celebrating the 1-year anniversary of their engagement -- so, is that back too?

Remember, it was just a week ago Sabrina went public about their split -- suggesting Odom is still dealing with personal demons that were getting in the way of their relationship.

"Y'all know I'm honest and transparent so I have to be the first to let you guys know that I am no longer engaged to Lamar," Sabrina Parr posted last Wednesday night on IG.

"Lamar has some things that he alone needs to work through," Parr said ...adding, "I love him dearly but I am no longer able to be by his side while he seeks the help he so desperately needs."

So, what changed? We're trying to find out.

40-year-old Odom had proposed to Parr (a fitness and life coach) at Myles Chefetz's Prime 112 restaurant in Miami back in November while dining with pal Nene Leakes.