need help is he cheating

hey guys I need some help. My finance and i have been together going on two years in may 28. Well me and him never use condoms at all. we have 1 son together and are currently trying for another baby. But I was looking three his stuff and found an unopened box of magnum condoms. But they expire may 2019. I asked him about it he said he brought them a couple years back before we got together??? they were hidden in 3 bags of grocery bags. is he cheating or is this possible????? and when would he had to buy these for them to expire next year.......