Okay So asking on behalf of my sister (she wouldnt listen to my opinion!!)?

So shes 13(almost 14) her boyfriend is 16(dont worry he only just turned it and is a really nice guy not interested in so please no comments on that! they are genuinley happy together!) Anyway so they sometimes will be watching TV on the sofa bed and will spoon, is it appropriate? is it wrong? they never go further than that just snuggling etc.. Views and opinions? Personally I think its fine maybe not all the time but like when shes upset and hes comforting her i think its fine!