Or they just feel a genuine connection with you and know you leave if you don't get the treatment you deserve.
well tbh i really want to believe that, but sadly, life is not a fairytale. even magic takes time. like, how can you know and sure you love someone when you barely know him/her? i bet it's more into self interest.. cause first year is a year you both get to know more deeper, get a lot conflict (the result of the collision of two heads trying to unite), cause there is no perfect person, they have flaws that hid during the process. that's why love is built.
and about the best treatment that you get in the first place, im referring to love bombing, and love bombing itself frequently involves an awesome and fast feel of affection. and yes i wouldn't disagree it feels great, but it won't last forever (only for months-a year). once they get bored of you, they will leave you easily.
Love bombing is marked by overwhelming affection intended to control, while genuine interest grows naturally by time, with consistent actions and mutual respect. mutual respect referring to consent, like you need to know their love language first, without assumption. and after you know, you try to show it and vice versa. try to read it, it's a very nice article that has been approved by psychology.
https://www.guillaumes.com/news/what-is-love-bombing
https://health.clevelandclinic.org/love-bombing