1. Straight girl MC arrives on an island that is cursed. Curse turns all people into same-sex couples. She makes friends with a guy in school that cross dresses (he atleast wears a skirt).

2. Male MC living with an alien. The alien looks like a normal human with long white hair but his true form is briefly mentioned to be grotesque. Alien has trouble to go back. Maybe he is also a wanted space criminal or a space royal in hiding.

Is the second one Sentaku no Toki?

It isn't. I gave sentaku no toki a go but it's not the one I am looking for. For one the alien was definitely an adult, there were more than 4 chapters scanlated by the time I read it (~20) and the drawing style of sentaku is way better than the one I'm looking for.