They said he lied, cheated, and I shouldn’t be involved with him. So I thought about what they said and talked to more people. It only shows them you are too immature to be in the relationship they are so worried about.
Another question you could ask them is What should my bf/gf do to win your trust? Remember, most of the time they are right and who wants to gamble with the few times they might be wrong, just for the sake of having a bf/gf.Ask you parents if they would be willing to meet with your bf/gf and have them explain their reservations to him/her.