Some of Lawrence’s topics, including son-mother relationships, women-women relationships, and of course men-women relationships, seem to beg for either a psychological approach or a feminist approach--or both--to understand how he treats these issues. Sometimes these critical approaches overlap. As for feminist criticism, in The Second Sex Simone de Beauvoir argues that Lawrence exemplifies patriarchal thought and practice in his claim that masculinity is by its nature primary (active, creative, and intellectual), while femininity by its nature is secondary (passive, earthy, and emotional). Another feminist critic, Kate Millet, argues in Sexual Politics that Lawrence's work is motivated by the desire to prevent women from entering man's world of intellect and action, thus depicting the independent woman as basically unnatural. In so far as Millet understands this desire asinsecurity and his fear of women (which Freud would label as “castration anxiety”), to which(according to Millet) Lawrence responds with an attack on women aimed at keeping them under men's control, we can see the psychological dimensions toMillet's essentially feminist approach. Both de Beauvoir and Millet wrote this criticism on Lawrence in the early 1970's, when feminism was very sensitive to the depiction of women in a work of literature.
I am not sure if Lawrence could be considered a "decadence" pioneer, as he came rather late to the movement but he certainly was attracted to some of it. By the early 20th century modernism was replacing decadence and Lawrence too moved away from the earlier style
I have a really good book on Lawrence called "The Choice" and fortunately I just discovered some blurbs about it online.
The work is called "The Vital Art of D.H. Lawrence" and in an odd way, this will help you with your question. Author Jack Stewart examines "Lawrence’s painterly vision" in Lawrence's novels. This "vision" focuses on "Lawrence’s attraction to nineteenth-century aestheticism and decadence."