From my personal experience, (it might not apply to teenagers here or in the western countries) for asians we shyly say ‘no’ but we mean ‘yes’. I’m not sure why it is like this.
When i first dated my boyfriend, i said a lot of nos to a lot of things (not only for sex, skinship or intimate relationship), though i somehow meant yes. I think there are queues/hints when we (asians) understand if ‘no’ is ‘yes’. It is difficult to explain. However, there’re times that no means no.