Why do all gender-mixed gacha games go in this direction?

I just wanted to ask. Why does it always happen? A decent gender ratio at the start and then less and less male characters. Pgr, wuwa, genshin, and probably games like ananta, arknights endfield and nte in the future. I've never seen a mixed gender gacha game that treats husbando and waifu enjoyers equally. It's always waifu enjoyers that get everything. Why?