You use eventing only when eventual consistency is acceptable. In your scenario, it sounds like it is not. So then you should use synchronous communication to e

You use eventing only when eventual consistency is acceptable. In your scenario, it sounds like it is not. So then you should use synchronous communication to ensure the expected experience is met. However, that also means that now you can't do stuff with service B without service A being up. So you're trading user experience against resiliency. Also, you should check your domains and bounded contexts and reevaluate whether A and B are actually different services. They might still legitimately be separate. Just something to check.