Kim Kardashian and Reggie Bush
02/14/2012 at 11:00 AM EST
Is an old flame heating up Kim Kardashian
's Valentine's Day this year?
Amid reports last weekend that the reality star reunited over lunch at the Beverly Hills Hotel with ex-boyfriend Reggie Bush, a source tells PEOPLE that the two are just friends – at least for now.
"They don't know what will happen," the source says. "They're taking it slow. They love each other so much and miss each other, but their relationship is so complicated."
Less than four months after announcing her split
from Kris Humphries after just 72 days of marriage, Kardashian, 31, who last called it quits
with the NFL pro, 26, in 2010, is in no rush to enter another relationship.
"Things are up in the air," the source adds. "Kim very much wants to take her time and be single and heal from her divorce."
Bush, who first stepped out with Kardashian in 2007, might also want to check in with stepfather Bruce Jenner.
"The next guy's got to go through me," Jenner said on Tuesday's The Ellen DeGeneres Show
. "I can tell if it's going to work or not."