The couple, who have been dating since 2018, are planning to marry, PEOPLE confirmed on Jan. 4.

A source said that Donald Trump’s oldest son and the former Fox News host-turned-political aide are engaged. “Kim has been wearing her engagement ring and both are very excited about blending their families,” the source added.

It’s unclear when the couple got engaged. No date has been set for the wedding, according to a source.

Guilfoyle seemed to hint at the news in the caption of an Instagram post made on New Year’s Day. The slideshow of images showed her and Don Jr., where she looked to be wearing a large diamond on her ring finger.

“Tonight was extra special celebrating @donaldjtrumpjr’s birthday,” she wrote. “Don, you are strong, smart, courageous, funny and the love of my life. I can’t wait to spend the rest of our lives together. Love you.”

Guilfoyle has been dating Don Jr. since around the time his ex-wife, Vanessa, filed for divorce in March 2018. Don Jr. has five kids with Vanessa — Donald III, Kai Madison, Spencer Frederick, Tristan Milos and Chloe Sophia — and Guilfoyle shares a son, Ronan, with ex-husband Eric Villency. She was also previously married to now-California Gov. Gavin Newsom.

Trump Jr. and his sister Ivanka were recently subpoenaed in the New York attorney general’s office ongoing civil investigation into whether the Trump Organization and its executives committed fraud.