Hi, i had this issue for the first time yesterday. So here's my scenario:
I was playing in desiderata Tal, with a family where one sim was created by me and his daughter (who had moved to college and eventually back). Said daughter was trying to get married (having a wedding party) with a pre made sim from university (mattias herz). I realized after googling it, that you cant marry young adult sims. So I played the pre made sim until he graduated and moved him to another lot in desiderata Tal.
Then I went back to this household, during the wedding party and was able to get married. They try to make a baby and I'm pretty sure she is pregnant, because the needs are going down fast. Next day I traveled to Twikki Island with both sims (the daughter and now husband. the father and the 5 dogs stay home). They stay at their vacation home (owned by the father).they visit the beach, book a boat trip, and up until that point everything is fine!
Then I try to go back to the vacation home, and that's the first time I get the infinite loading screen of death. As it was already mentioned here, i was able to hear the audio (some piano music, which checks, cause they had a piano at the house, and some sims desperate screaming, maybe more but I dont remember). Anyways, I didnt close the game, just had it running on the background.
So today I check my pc and it still hasn't loaded. I used task manager to force close it. Then I updated the game and went back to the family in desidera tal, I got the popup that they were on vacation, so I agreed to go play in twikki island. And the game is still loading while I wrote all this
:(