Jimmy and the condoms

I don't understand why Jimmy broke up with Amy just because she had condoms in her purse. He knew she had John and I would assume Amy told Jimmy a little about how she wasn't prepared at all for sex and now she has the condoms just in case. I think its smart for Amy to have them because she realized things do sometimes happen unplanned, and just because you have condoms doesn't mean you are going to use them right away.