The dating app Bumble is being sued by the competing dating app Tinder’s parent company Match Group. The lawsuit alleges intellectual property theft, claiming among other things that Bumble is using Tinder’s method of swiping right for like and left for dislike and only matching based on mutual right swipes.

Some intellectual property disputes have more of a backstory than can be seen in the Statement of Claim. In this case, Bumble was founded by an early Tinder employee. Some of the claims in the lawsuit involve the theft of trade secrets and allege that ex-Tinder employees took confidential information to Bumble. Match Group has also made efforts to purchase Bumble. Bumble has now counterclaimed for the theft of trade secrets and proprietary information as well.

Bumble responded to the suit not only by filing their countersuit, but also by publishing an open letter in response, and by taking a full page advertisement in the New York Times sending a cheeky but firm response to Tinder that they were “swiping left” on them.

This case is in the very early stages, so it is difficult to tell which party has the upper hand. What does seem certain at this case is that both the suit and countersuit were motivated in part by bad blood between the founders of both companies.