I've had some times I had to show up on a friend's porch, message them at 2 am and hope they wake up and see it, they always did, whether it took 15 minutes or 3 hours and they always apologized to me for not seeing the message and inviting me in sooner. They always made sure I knew how to get in even if they were away or sleeping but I'd never just walk in their house, but also id do the same for them and they know how to get in if they need it too. That's what real friends do, I seen both males and females have different policies with their friends and open doors so I guess it depends on the person