Trying to find loops in an Undirected Graph

Question

I am trying to write an algorithm that finds out if the vertex I am entering into a Graph is forming a triangle loop with surrounding Vertices. My algorithm however never returns true and I don't know why.

    private static bool IsCyclic(UndirectedGraphStructure graphStructure, int vertexA, int vertexB, int startingVertex, List<int> connectionList)
    {
        //go two steps
        //check if you reach the original one again after going two steps

        //I want to go through each connection of a given vertex and look at the connections of all the connections of that vertex and if that equals the original then its a loop
        // A -> B -> C <= has A in it?
        

        for (int i = 0; i < graphStructure.Adjacent[vertexA].Count; i++)
        {
            if(graphStructure.Adjacent[vertexA][i].isForward)
            {
                for (int j = 0; j < graphStructure.Adjacent[graphStructure.Adjacent[vertexA][i].connection].Count; j++)
                {
                    if(graphStructure.Adjacent[graphStructure.Adjacent[vertexA][i].connection][j].isForward)
                    {
                        for (int l = 0; l < graphStructure.Adjacent[graphStructure.Adjacent[graphStructure.Adjacent[vertexA][i].connection][j].connection].Count; l++)
                        {
                            if(graphStructure.Adjacent[graphStructure.Adjacent[graphStructure.Adjacent[vertexA][i].connection][j].connection][l].isForward)
                            {
                                if (graphStructure.Adjacent[graphStructure.Adjacent[graphStructure.Adjacent[vertexA][i].connection][j].connection][l].connection == vertexA)
                                {
                                    return true;
                                }
                            }
                        }
                    }
                }
            }
        }

        return false;
    }