I remember i read that if two people pray salah but they don’t pray it in congregation, they each pray their own in the same house at the same that their salah is valid. After some time i did this but in my mind i gave the excuses that maybe he’s praying sunnah so i pray my own even tho i doubted it

Ustadh AbdulAziz al-Haqqan

Praying alone is valid, but many ulama mentioned that it is mandatory to pray in congregation.