It's been a week since my boyfriend cheated on me and I'm already over it... why?

He gave a good excuse that you accept it. Or, you don't really love him that much, so you don't really care.

From your question it sounds like you expected to feel much more hurt than you are. Is that correct? If so, why? Is it because society taught you that you're "supposed" to feel a certain way? One might suggest (and of course, only YOU can know what you're thinking) that maybe you aren't that attached to the fellow? Maybe you aren't shocked by his behavior? Maybe you aren't even that interested in continuing the relationship, and this is all the reason you need to end it? Either way, I hope you use the experience to really think about what you expect from a partner, how you wish to be treated, and if this is someone you hope to continue a relationship with or not. Most of all, I hope you find happiness and peace!