English is not my first language, sorry if there is mispelling
Ok for those stuck with "the friendship/non romantic..." message with Sans route, here what I did:
-Follow the walkthrough
(Note: it also didn't work the first time I tried so I decided to change some choice that are not in the walkthrough, I don't know which ones trigger Sansroute...so have all of them :/)
-At home:She always returns the favor anyway. When things get stressful for you, she'll pick up your favorite treat from Grillby's and do your laundry while you relax.
-You make sure to pick up food from Grillby's before you head over.(I know this is in the walkthrough but I put it there in case some get confused)
-Gaster:He's is absolute legend in his field, you had nothing but respect for him.
But then you got to meet him.
He's nice enough. You're happy for your sister.
-Papyrus:He's a diligent monster, and you don't want to get in him in trouble by entering without permission, but. . .
-2nd floor:You want to explore this floor further.(still in walkthrought but just in case)
-You can pick one of those choice:Fear momentarily paralysizes you./Your stomach lurches in anxiety, uncomfortable by what you saw.
-Keep exploring
-Sans:You are stupidly, one-sidedly in love with him.(If you see that choice then congratulation you are in Sansroute)
-before reading the chat:Your heart thumps in your chest as you read the messages between your sister and Sans.ATTENTION !!! if you not see that choice specifically then you miss something
This is the longest post I have ever made XD I hope this can help some of you, and that you could understand what I write