The neutron star followed an oval trajectory before it collided with a black hole.

 

“Artist’s impression of an eccentric neutron star–black hole binary. The neutron star’s path is shown in blue and the black hole’s motion in orange as the two objects orbit each other. The eccentricity shown here is exaggerated compared to the real system, GW200105, to make the effect on the orbital motion clearer. Credit: Geraint Pratten, Royal Society University Research Fellow, University of Birmingham” (ScitechDaily, Scientists Spot a Black Hole-Neutron Star Pair Breaking the Rules of Cosmic Orbits)

The neutron star’s unusual trajectory when it fell into a black hole. The thing that formed that unusual oval trajectory could be the third component. There could be a possibility. That there was something unseen. Maybe the second back hole in the system before the final impact. The third participant can be outside the system. Or maybe it's very close to the back hole. 

The neutron star and black hole collided, and this thing defies predicted models. The neutron star impacted the black hole following an oval trajectory. This means that the closest point in that trajectory moved closer and closer to the black hole. And then the black hole pulled that neutron star inside it. The reason for that trajectory is that the neutron star got more energy when it closed the black hole. 

Similarly, in cases where black holes merge with neutron stars, they also have their own material disk. The impact of material disks will create energy, which pushes the neutron star away from the black hole. This also explains gamma-rays. From those mergers. 

The material disk interacts with the black hole material disk, and that forms energy. So this means that the shape of the trajectory remains similar. But sooner or later, the black hole “steals” the neutron star’s material disk. This means that the neutron star will not get as much energy from the impact of those material disks. This means that the black hole pulls the neutron star closer and closer to it. 

https://scitechdaily.com/scientists-spot-a-black-hole-neutron-star-pair-breaking-the-rules-of-cosmic-orbits/