Earlier this week, it emerged that Momsen's role on the show has been cut down and she will miss at least four episodes, starting with the midseason finale.
Sources have now told E! Online that the claims are true but insisted that Momsen "isn't going anywhere".
The insiders explained that Momsen has a contract through to the seventh season and will continue to appear in the series, just not in every episode. They also confirmed that Momsen's absence is for creative reasons.
"Jenny isn't in college like everyone else, so it's hard to weave her into the central storylines," a source said. "We don't want to just bring her in to hang out at the breakfast table with Lily and Rufus and say a line or two - we want a reason to have her there."
Another insider insisted that Momsen is popular on the set despite guest star Tim Gunn's claims that she is a "diva".
"Everyone likes her," the source said. "Her absence really is driven by the story. Anything else is speculative."
Representatives for Gossip Girl and Momsen have not yet commented on the reports.