To Service or not to Service

Hi all,

I have a simple expense tracking system in which a user makes a Claim and this can contain multiple Expense(s) and I made a service class to handle CRUD. Something I'm struggling with is this: as an expense can only exist in a claim, should a ClaimService be responsible rather than my existing ExpenseService?

Here's how that looks:

<?php
namespace App\Services;

use App\Models\Expense;
use App\Models\ExpenseClaim;
use App\Models\User;

class ExpenseService
{
    public function retrieveExpenses(ExpenseClaim $expenseClaim)
    {
        return $expenseClaim->expenses()->get();
    }

    /**
     * Create an expense within a claim.
     *
     * @param \App\Models\ExpenseClaim $expenseClaim
     * @param \App\Models\User         $user
     * @param array                    $attributes
     *
     * @return App\Models\Expense
     */
    public function createExpense(ExpenseClaim $expenseClaim, User $user, array $attributes)
    {
        return $expenseClaim->expenses()->create([
            'user_id' => $user->id,
            'expense_date' => $attributes['expense_date'],
            'business_reason' => $attributes['business_reason'],
            'category' => $attributes['category'],
            'project_code' => $attributes['project_code'],
            'is_foreign_expense' => $attributes['is_foreign_expense'],
            'currency_code' => $attributes['currency_code'],
            'conversion_rate_to_gbp' => $attributes['conversion_rate_to_gbp'],
            'amount_before_conversion' => $attributes['amount_before_conversion'],
            'gross_amount' => $attributes['gross_amount'],
            'has_vat' => $attributes['has_vat'],
            'vat_claimed' => $attributes['vat_claimed'],
        ]);
    }

    /**
     * Undocumented function
     *
     * @param \App\Models\Expense $expense
     * @param \App\Models\User    $user
     * @param array               $attributes
     *
     * @return App\Models\Expense
     */
    public function updateExpense(Expense $expense, User $user, array $attributes)
    {
        $expense->update([
            'user_id' => $user->id,
            'expense_date' => $attributes['expense_date'],
            'business_reason' => $attributes['business_reason'],
            'category' => $attributes['category'],
            'project_code' => $attributes['project_code'],
            'is_foreign_expense' => $attributes['is_foreign_expense'],
            'currency_code' => $attributes['currency_code'],
            'conversion_rate_to_gbp' => $attributes['conversion_rate_to_gbp'],
            'amount_before_conversion' => $attributes['amount_before_conversion'],
            'gross_amount' => $attributes['gross_amount'],
            'has_vat' => $attributes['has_vat'],
            'vat_claimed' => $attributes['vat_claimed'],
        ]);

        return $expense;
    }

    /**
     * Remove an existing expense.
     *
     * @param \App\Models\Expense $expense
     *
     * @return bool
     */
    public function deleteExpense(Expense $expense)
    {
        $expense->delete();

        return $expense;
    }
}

Then in my controller:

<?php
namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Http\Requests\StoreExpense;
use App\Models\Expense;
use App\Models\ExpenseClaim;
use App\Services\ExpenseService;

class UserExpenseController extends Controller
{
    protected $expenseService;

    /**
     *  Create a new controller instance.
     *  Pass in our expense service class
     *
     * @param \App\Services\ExpenseService $expenseService
     */
    public function __construct(ExpenseService $expenseService)
    {
        $this->expenseService = $expenseService;
    }

    /**
     * Show a listing of expenses for a given user.
     *
     * @return void
     */
    public function index(ExpenseClaim $expenseClaim)
    {
        $expenses = $this->expenseService->retrieveExpenses($expenseClaim);

        return response()->json($expenses, 200);
    }

    /**
     * Create a new expense inside an expense claim for a given user.
     *
     * @param  ExpenseClaim $expenseClaim
     * @return void
     */
    public function store(ExpenseClaim $expenseClaim, StoreExpense $request)
    {
        $this->authorize('update', $expenseClaim);

        $attributes = $request->validated();

        $expense = $this->expenseService->createExpense($expenseClaim, auth()->user(), $attributes);

        return response()->json($expense, 200);
    }

    /**
     * Update  an existing expense in an expense claim for a given user.
     *
     * @param \App\Models\ExpenseClaim $expenseClaim
     * @param \App\Models\Expense      $expense
     *
     * @return void
     */
    public function update(ExpenseClaim $expenseClaim, Expense $expense, StoreExpense $request)
    {
        $this->authorize('update', $expenseClaim);

        $attributes = $request->validated();

        $expense = $this->expenseService->updateExpense($expense, auth()->user(), $attributes);

        return response()->json($expense, 200);
    }

    /**
     * Display a specific expense within an expense claim
     *
     * @param  ExpenseClaim $expenseClaim
     * @param  Expense      $expense
     * @return void
     */
    public function show(ExpenseClaim $expenseClaim, Expense $expense)
    {
        $this->authorize('update', $expenseClaim);

        return response()->json($expense, 200);
    }

    /**
     * Delete a given expense for a given user.
     *
     * @param  ExpenseClaim $expenseClaim
     * @return void
     */
    public function destroy(ExpenseClaim $expenseClaim, Expense $expense)
    {
        $this->authorize('update', $expenseClaim);

        $expense = $this->expenseService->deleteExpense($expense);

        return response()->json($expense, 200);
    }
}

My thought was that admin need to view submitted claims so a service class made sense, but how do you follow Single Responsibility if one thing can't exist without the other?

Thanks in advance.