お互い自分はとても恥ずかしいけど相手が平気そうにしてるから、ウブだと思われたくなくてがんばって平気なふりをしているカップルさん

Both of them are embarrassed, but since their partner seems ok with it, they don't want to be thought of as inexperienced, they're pretending to be ok with it.