School Banned Me From Campus For An Unjust Reason, Is There Anything I Can Do?

LONG POST SORRY!

For context, I (F) go to a college that shares a campus with another college in the US. My partner (M) goes to the other college.

I was close friends with his roommates (F&F), and we were often physically affectionate (hugs, leaning on each other, kissing on the cheek). About a month ago, my partner and I got into an argument, and we stopped talking for a week. I didn't want this to affect my relationship with his roommates, so when I saw one of them, I gave her a hug and a kiss on the cheek. I should have asked for permission, I know, but I didn't think twice about it because I considered such affection normal between us. I told her I loved her, and she told me she loved me as well. I asked her during the period my partner and I were not in contact if she was mad at me-- I wondered if she was upset with me for the same reasons my partner was-- and she said no.

After the week, my partner and I started talking again and sorted out our issues. I also found out that our friend was very uncomfortable with the intimacy I had engaged in with her. She had verbally told my partner that it was okay if he brought me over to their dorm. I reached out to try and apologize over text and possibly in person. She accepted the text apology and refused to meet me in person, which I respected. When I went over to my partner's dorm, I mainly stayed in his room and only left to use his bathroom (which he did not share with anyone else). She did not see me, but she could have possibly heard me talking, which I am sorry for.

After a week, I received an email from my school's Title 9 (discrimination/sexual harassment) office as well as his school's RD. I was banned from all of his college's property, and my presence on their property would first result in a warning then law enforcement. However, when I reached out to my school's Title 9 office to further understand this issue, they said it was not because of the Title 9 as they found no reason to investigate. I would understand this situation more if the Title 9 case was investigated.

The reason my partner's school gave was that he did not register me as a guest 24 hours in advance before I visited the property, which is against the student handbook. I am not a student of his college, so I didn't know the rules/could not register myself as a guest. For me, it seems as if they were digging for any reason to ban me once they realized the Title 9 offense was not going to be investigated. It feels unfair that they would pin this reason on me because I could not do anything about it. I also feel that they should have given a warning before outright banning me.

Especially since my partner has moved out of the dorm he shared with his roommates, I was wondering if I had any legal standing to try to appeal the punishment and be allowed to enter the property again. I will put in my best effort to avoid her if that makes her more comfortable. Do I have an argument I can make?