Gomi Gojo's Territory Opening Gesture was an important element in the " Return of Curse ". Gotto Gojo's domain was displayed as 'Boundless Empty'. This gesture was to pull the enemy into the infinite inner side, forcing the enemy's brain to produce a large amount of information, causing the brain to lose its function and could only stand and wait for death. Although there was no specific description of the hand gesture, it could be speculated that the hand gesture was to expand the domain through a specific posture of the hands.
Marin does confess to Gojo in the manga. It happens during a crucial moment when their relationship reaches a turning point. The confession is filled with honesty and vulnerability.
Well, it depends on how you interpret the story. Technically, Gojo Satoru's fate is quite complex and can be seen as a sort of death in some respects, but there are also elements that leave room for interpretation.