How to ask for a break

Okay so I been with my boyfriend for 6 months and his cousin told him a rumor about me and he said he trusted me and didn’t care about but now all of a sudden he keeps bringing it up and it’s hurting me bc I feel like he really don’t trust me I just don’t wanna be in the relationship anymore more but don’t wanna break up bc I don’t want to ruin his holidays. Help please