It seems more like falling in lust than falling in love

I don't think anybody here could shed light on the *why* of your behaviours as no one is the expert on you. What you state "I still don't know why I actually do it, maybe seem to need it even" seems very pertinent and I would explore this with a trained professional so as to get insight on *you*

I don't know how well you know yourself but this could help you identify this 'need' to find something that you can't seem to obtain.