If the person Ive loved more than anyone else in the world came to my door, I'd be very surprised. We've spent the past two years avoiding each other because of a complicated love triangle (which then became a love square)
We are becoming friends again now, but not to the extent that he'd be at my door.
First, I'd assume he was there to see someone else in my house, as they vaugely know him, but if he told me he was there to see me, I'd be surprised, delighted, and overwelmed. I have very intense feelings about him and our joint past, so I'd probably get quite shaky and faint. I'd offer him a drink, bring him in, and be nervous and apprehensive about what he wanted, but excited, and hopeful too.
I get the same worries about calling on people unannounced. It's actually something I have a phobia of, nothing I can think of a name for other than "being where Im not supposed to be". Ive never found anyone who shares it. It's a sort of fear of being somewhere without an invite, a heightend sense of territory and politness. I used to hide behind the sofa when my mum put alice in wonderland on the tv because she goes to the mad hatters tea party uninvited. The bit where they discover her and tell her off for gatecrashing made me terrified, even as a toddler. So yes, I understand its scary to call on someone unannounced.