Worried?

So for the first time ever my husband and I were having sex like usual when he suddenly said let's have a threesome. It didn't shock me because I was the freak in our relationship. So me being me I agreed but the shocking thing was he kept asking me who's penis did I want in me and he kept saying "you want me to f*ck another b*tch?" At this point he claims that he was in the mood and was "role-playing". Well at this point I began thinking to myself "is he trying to cheat? Is he tired of just having me?". We've been together 5 years and and married for 2 years. Would you consider a threesome to be cheating?