<ul th:each="users : ${relationships}" id="in-request-list">
            <li>
                <p th:text="${users.firstName}"></p>
                 <button th:onclick="'accept(' + ${users.firstName} + ');'" id="accept">Accept</button>
                <button id="not-accept">Not accept</button>
            </li>
        </ul>

 $("#accept").click(function accept(e) {
        $.ajax({
            type: "POST",
            url: "update-relationship",
            data: {status: "friend", user: e},
            success: function  success() {
                alert("updated");
            },
            error: function error(xhr) {
                debugger;
                alert("not updated");
            }
        });
    });