Establecer el SelectedItem de un picker en Xamarin Forms MVVM a un valor.

Soy nuevo en Xamarin.Forms y MVVM. Tengo el siguiente picker en XAML:

<picker title="Estado Civil" x:name="maritalStatus" margin="10,5,10,0" itemssource="{Binding MaritalStatusList}" itemdisplaybinding="{Binding Value}" selecteditem="{Binding SelectedMaritalStatus, Mode=TwoWay}">
</picker>

Así es como configuro la lista de elementos:

public class KeyValuePair
{
    public int Key { get; set; }
    public string Value { get; set; }
}

public static class MaritalStatus
{
    public static List<keyvaluepair> GetMaritalStatus()
    {
        return new List<keyvaluepair>()
        {
            new KeyValuePair() {Key=1, Value="Soltero(a)"},
            new KeyValuePair() {Key=1, Value="Casado(a)"},
            new KeyValuePair() {Key=1, Value="Viudo(a)"},
            new KeyValuePair() {Key=1, Value="Divorciado(a)"},
            new KeyValuePair() {Key=1, Value="Pareja de hecho"}

        };
    }
}

Y así es como configuro la propiedad:

KeyValuePair selectedMaritalStatus;
public KeyValuePair SelectedMaritalStatus
{
    get => selectedMaritalStatus;
    set
    {
        SetProperty(ref selectedMaritalStatus, value);
        MaritalStatusText = selectedMaritalStatus.Value;
    }
}

string maritalStatusText;
public string MaritalStatusText
{
    get => maritalStatusText;
    set
    {
        SetProperty(ref maritalStatusText, value);
    }
}

Lo anterior muestra correctamente la lista en el picker. Mi problema es que tengo un formulario y quiero establecer el picker con el valor que proviene de una base de datos. Tengo algunas otras entradas que puedo configurar correctamente desde un ViewModel de esta forma:

foreach (EmployeeDetails details in EmployeeDetailsService.EmployeeDetails)
{
    Id = details.Id;
    ADEmployeeID = await new MSGraphService().GetUserIdAsync();
    FirstName = details.FirstName;
    MiddleName = details.MiddleName;
    LastName = details.LastName;
    Street = details.Address.Street;
    Block = details.Address.Block;
    City = details.Address.City;
    County = details.Address.County;
    PostCode = details.Address.PostCode;
    Telephone = details.Telephone;
    DateOfBirth = details.DateOfBirth != null ? DateTime.Parse(details.DateOfBirth) : DateTime.Now.Date;
    CountryOfBirth = details.CountryOfBirth;
    SelectedMaritalStatus.Value = details.MaritalStatus;
    //MaritalStatusText = details.MaritalStatus;
    PassportIssuingCountry = details.PassportIssuingCountry;
    PassportNumber = details.PassportNumber;
    PassportExpiryDate = details.PassportExpiryDate != null ? DateTime.Parse(details.PassportExpiryDate) : DateTime.Now.Date;
    BankName = details.BankName;
    BankAddress = details.BankAddress;
    BankSortCode = details.BankSortCode;
    NationalInsuranceNumber = details.NationalInsuranceNumber;
    //    //! Need to add P45
}

El picker de estado civil es el único que no puedo configurar, todo lo demás funciona.

• ACTUALIZACIÓN *

Este es mi SetProperty:

protected bool SetProperty<t>(ref T backingStore, T value,
        [CallerMemberName] string propertyName = "",
        Action onChanged = null)
    {
        if (EqualityComparer<t>.Default.Equals(backingStore, value)) { return false; }

        backingStore = value;
        onChanged?.Invoke();
        OnPropertyChanged(propertyName);
        return true;
    }

    #region INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
    {
        PropertyChangedEventHandler changed = PropertyChanged;
        if (changed == null) { return; }

        changed.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

Cualquier ayuda sería muy apreciada.