You are indeed right that Marie appears to have an obsession with purple, which is very clear in the earlier seasons (she's always wearing something purple) and as you've shown in your screencap her home is very much covered in purple furnishings.
The origins of this obsession are covered in an interview with Betsy Brandt (the actress who plays Marie) by AV Club:
In the beginning, my character… I didn’t have a lot of text, so I didn’t have a lot to go on, so I went with what I had. We were all assigned a color—mine was purple—and I said, “Well if her color is purple, then I think she just loves purple. She is really, really into purple.” She’s that kind of person. She doesn’t do anything half-assed. And Vince said, “Great!” And now everybody’s color has changed except for mine. I’m like, “How come everybody else’s color is changing, and mine’s not?” And [costume designer] Kathleen Detoro said, “Vince likes you in purple.” [Laughs.] So I’ve kept the purple, but then they’ve added in yellow, and this season I’ve had maybe one or two things that were black.