I have this issue only with new saves but there I use now flauschtrud mod, which fix this thing.
In my old save my townies get created as it should be. Romantically attracted is empty, exploring is on yes, and WooHoo interest is in both.
In my new save they always end with romantically attracted No, exploring No and WooHoo neither. So, I got a bunch of Asexual/Aromantic sims which will not change the sexual preference because exploring is on no. So, the player need to edit all created townies in vanilla and change exploring to yes and change interest in WooHoo if you want to WooHoo.
