IF Seal: How can I model and signpost shifting relationships?

hi seal! i'm writing this question out as i go so hopefully it all makes sense. in the if i'm planning out, i'm allowing the MC to be able to not have any close relationships with the NPCs, the plan is to keep that up until the end but, hey, who knows when traumabonding is involved. anyways, i'm reasonably confident i can keep the cast and MC together even with this dynamic (forced proximity, same goals, etc) but i'm not quite sure how to differentiate between those who actually want very little to do with the NPCs and those who want to do a slow burn rivals to lovers thing. the part i'm going back and forth on is when and how do i signal to the players that it's time to either choose to move the relationship up or keep it as is without making it feel forced, and also how to portray the differences on how fast/slow the relationship is progressing (example: moment 1 is where MC can confess and moment 2 is where MC and NPC can start dating, if MC doesn't confess in moment 1 but instead…