How to know

How do you know if someone is actually busy or they’re just not that interested in you? There’s someone i really like but i’ve asked out 3 times now and every time there’s something going on. Now i’ve never formally asked out on a date, I usually ask to hang out on the same day if they could find an hour for coffee, lunch or dinner (whatever works for them) but it never happens. I don’t know if I should keep trying (I’m usually persistent on the things i like but don’t wanna seem a creep) or just drop it and move on. I really like them tho.