Radar stealth is actually only of limited utility in fighters because it only confers a dubious and questionable advantage at ranges beyond that of electro-optical systems.
Electro-optical systems use Infra Red, which gives them a passive detection range of ~30-40km depending upon conditions, whereas active radar gives detection ranges of several hundred km. However, the use of active radar not only immediately alerts any enemy that you're looking for them before you are able to detect them (because the strength of the incident radar pulse received by the target aircraft will be far stronger than the reflected signal from the target aircraft that the radar needs to receive and recognise) but also acts as a beacon for your location.
Note that electro-optical systems using IR can work by detecting skin-heating - they don't need to see the hot exhaust plume from the engines - and so can detect an oncoming aircraft as easily as one retreating or flying across its path.
The options for radar stealth fighters, when engaging electro-optical equipped fighters, are either to retreat and maintain distances beyond electro-optical detection i.e. 30-40km, or close to within electro-optical detection range where their radar stealth is useless and where any aerodynamic compromises due to radar stealth might leave them at a distinct disadvantage. This is why non-radar stealthy but highly agile fighters, such as the Gripen and Eurofighter, and especially the Sukhoi Flanker variants, which are aerodynamically superior to all other current fighters, including the F-22, are still viable.