There arent any laws around being in a non-sexual relationship where one person is under 18 and the other over. Once you turn 16 its not illegal for someone to have sex with you no matter how old they are. Something else to think about would be how the relationship is going to work.
Can a 16 year old be in a relationship with a 20 year old?
Its generally legal for a 16 year old and a 20 year old to have sex in OK.
Can you be 21 and date a 16 year old?
Generally, it is not illegal for these two to date. Of course, any sexual activity is considered statutory rape, but if there is no sexual aspect to their relationship, then they are probably fine. However, this is a fine line to walk for the 21 year old.
Is it weird to find 16 year olds attractive?
Its not unusual for a typical 16-year-old to be attractive to many men and the younger we go the fewer and fewer men are attracted to that age group. Ephebophilia is used only to describe the preference for mid-to-late adolescent sexual partners, not the mere presence of some level of sexual attraction.
Is it wrong to date a 16 year old 25?
Dating is legal but you are not of an age to consent to sex at 16. However, even though it may be legal, it is still not a good idea. Your parents could also try getting a restraining order against him.