she was 16 and i was 19
i know it would have been illegal if i had sex with her, but if we just met without doing that, her dad would have known where she was and who she was with
If you'd met her in the UK when she was 15 and you were 18, you could have been charged with sections 14 and 15 of the Sexual Offences Act 2003, even if you hadn't had sex with her. It would then be up to the court to decide what your intent was, and since there would be a forensic examination of your computer, any chat logs recording your romantic attachment to her would become evidence against you, as would any logs of sexual banter.
14. Arranging or facilitating commission of a child sex offence15. Meeting a child following sexual grooming etc.If you'd had sex with her, you could have been charged with section 9:
9. Sexual activity with a childSince she had Asperger's syndrome and/or other mental issues, you could have been charged with section 30:
30. Sexual activity with a person with a mental disorder impeding choiceIf she was coming into the UK from another country, you could have been charged with section 57:
57. Trafficking into the UK for sexual exploitationIf you'd given her alcohol, you could also have been charged with section 61, on the basis that a child cannot give consent to be intoxicated.
61. Administering a substance with intentIf you were given so much as a caution on any of these offences, you'd be placed on the sex offenders register for a minimum of 2 years. You might also be issued with a SOPO, which is a restraining order forbidding certain behaviours. The first person to be issued with one was forbidden to be within 100m of a school or play area at any time, from being alone with children, from being in the same house as a child, accompanied or otherwise, and was given a life ban from using the internet.
It may seem rather extreme, but stranger things have happened, and continue to happen with some regularity.