slow burn is a perfectly acceptable thing. and they're definitely moving. the mc is coming to terms with his feelings, and they've started to recognize each other's feelings. and narratively, it makes sense for them to move much more slowly than the second couple--not only because of their circumstances and personalities (and history), but because it would be boring and unnatural if the main couple had insta-love.

legit only reading this for the second couple because the first is absolute dog shit