A lot of wonderful energy, time and diligence goes into raising happy, well adjusted, capable kids and oftentimes the parents identity changes significantly through this process.
Whether one views this as a "loss," may be determined by the person's perception of this process in life. The process of sacrifice and dedication toward raising these healthy children.
While I understand clients who say they have lost their identity, my role as therapist and guide may be to reframe this perception into a view of a change in identity or a creation of a new identity.
One may never return to their former identity such as who they were before marriage or before having kids, but this person takes all of their roles with them going forward in life.
One may never be able to return to "who they were" but they can incorporate "who they were along with who they are" and "who they want to be."
Me + the new me + the future me = a more self actualized me.