"This is something Khloe has wanted for years and years and yet it's more than that: she didn't want it unless she was in the right relationship for it". Soon after posting the first photos, Jenner also posted a video of herself that gives viewers a closer shot of her dramatic Halloween makeup.
"I just want a good body", she tells him in a confessional during which he suggests they enjoy one final delicious meal before she starts her new routine.
Khloe has called Thompson "dad" before.
Reality star Khloe Kardashian is known for her often over-the-top style, so it comes as no surprise that she and her boyfriend Tristan Thompson would go all out for Halloween.
"This is such a wonderful moment for her, not only is she going to be a mother, she is going to be raising a child with a man she truly loves", the source added.
Khloe Kardashian is pregnant, but her baby bump barely showed in her Halloween costume. "I honestly could not have imagined a better last supper", she says after her day out with Khloe and Jonathan.
But a few followers seemed to spot an apparent "lack" of baby bump in the photo. Pictured: Kardashian arrives at the Kardashian Kollection cocktail party at the Park Hyatt Guest House on November 19, 2013 in Sydney, Australia.