My gf(24) of 5 months is jealous of the sexy/kinky clothing I bought her for our date

I bought her very expensive sexy/kinky clothing for our date and she got really upset and said it was creepy. I confronted her and she admitted that she thought I bought it to cheat on her with other women. I don’t know what to do because I confronted her and she didn’t back down on it and I think she is dealing with insecurities from her past relationship but I don’t want her to deal with those issues in my relationship.