OK I tried everything as u suggested and my relation with 3-4 jocks reached above 70, others are above 30-40 also I warned Sonia throughout her slut transformation. Every day I'm only interacting with them in school,beavh,gym,field as much as possible and solely focused on them. It's been 5 months since but I don't see any progress with them or popular group ,instead nerd group slightly increased. Is this a bug?
It is hard to say, but if you are only close to 3-4 of them and then you have Christina who hates you. That means you are only earning 2-3 points a day plus any stuff you do during school or at the disco they like, minus any points where you do stuff they don't like. If you are doing as much stuff they don't like, as do like. Then you might only be earning like 2 points a day, if that is the case no it is not a bug.
The fastest way to be friends with them is be friends with ALL the jokes other than Christina.
Some other stuff to do
Wear a uniform they approve of
Slap boys that bother you
Pick on/bully nerds, outcasts and others
Dance well at the disco
Do well during PE class
Joining volleyball, track, starlets, or cheerleading
Don't ask questions in class or do nerdy stuff, if you do bad at PE you lose points, if you dress to slutty or conservative you lose points, if you dance badly at the disco you lose points etc
So I don't think it is a bug. When I said it takes 2-3 months I was talking about if you become friends with all of them and you don't do things to lose points with them, you can hit the cap which is earn 10 points a day or 70 a week. Then depending on where you started it would take roughly 2 months from there give or take a bit and it normally takes about a month to get all the friendships up for a total of 3 months. It can only take 2 months if you are on a start that is liked by another group, like cool kids to jocks as they tend to like each other so less time to get friendships up and your start value is higher. Or longer if you are making a harder jump like nerd to jock, as you are likely not doing well in PE you might be losing some points on those days.