Is it normal to get so annoyed to see cum stains on my parent's bed

Hi, I just turned 18, so I still live with my parents. From time to time, my mom and I would watch movies in her bed (I'm a girl, using my friends old account), now, it's not like I was snooping around on her bed, she invited me, and out of nowhere I see these big white stains (her sheets are brown), and she seems to just think I'm okay laying in that, so now I lay on the top covers. Also, I get bothered when I see her sex toys and jellies laying around. I know they are a couple, but it just bothers me a lot. Is this normal?