Explanation
Not necessarily; it doesn't mean that ~.
Formation
Verb-plain + わけではない, い-Adjective + わけではない, な-Adjective + だわけではない, Noun + だわけではない
Detailed explanation
The ～わけではない grammar point is used to express that something is not necessarily the case or 'it doesn’t mean that...' It negates a broad assumption or generalization.
Examples
Kare ga benkyou shinai wake dewa nai ga, seiseki ga amari yoku nai.
It's not that he doesn't study, but his grades aren't very good.
Kono resutoran ga takai wake dewa nai kedo, mainichi kayou ni wa sukoshi takai ne.
It's not that this restaurant is expensive, but it's a bit too pricey to go there every day.
Kanojo ga yasashikunai wake dewa nai ga, tokidoki hanashikata ga kitsui koto ga aru.
It's not that she's unkind, but sometimes her manner of speaking can be harsh.
Kare ga isogashii wake dewa nai ga, jikan o jouzu ni tsukaete inai you da.
It's not that he's busy; he just doesn't seem to use his time effectively.
Practice
Grammar content sourced from hanabira.org.