"Love Island USA" stars Olandria Carthen and Nic Vansteenberghe are proving some vacation romances don't last forever ... because the runners-up on the show's 7th season have split ... TMZ has confirmed.

The reality TV couple decided to part ways recently ... about a year after leaving the villa as a couple. PEOPLE was first to report the split.

As for the reason behind the split ... a source told PEOPLE, "The distance between them and their busy schedules made it challenging to maintain their connection. They still remain close friends. They share a deep love and respect for each other and will always support one another whenever possible.”

The pair coupled up days before the finale of Season 7 ... despite saying they had instant chemistry. Up until that point, the two had coupled up with other people.

While they first shared their relationship with fans, the pair quickly started posting each other less ... with Olandria telling Glamour in December they were super drained by all the attention -- and they hoped sharing less would help.

Instead, Olandria told the outlet rumors started swirling because they didn't post each other ... putting them between a rock and a hard place.

We've reached out to the couple ... so far, no word back.