It's up to you to decide when to give up? How much can you handle? Is your marriage worth saving to you? Don't listen to all that I don't love you it's too late blah blah blah crap right now. It's up to you, but DBing is to save you and make you better.
You know your wife best. Dbing, Gal, and detaching are for you to become a better person. The changes you make must be permanent. What are your wifes complaints about you? Are they legit. How long has she been unhappy with you and your R?
Generally MLC starts out with a spouse begining to withdraw from the R very slowly. Then there is an overlap between the withdraw and anger. Has she been cold, angry, and blame things on you. Does she project her feelings on you? Is she self absorbed and numb to everyone's feelings but her own.
How was your wife's childhood. Did she have any trouble with her mother or father when she was young? That is usually an underlying issue. Depression is also a major issue.
Think back a few years have either of you had any major life changes to possibly trigger MLC. ie: death of a close relative,job change,job promotion,kids leaving home.
Have you noticed any change in the way she acts, dresses, music she listens to. MLC'ers will generally be the opposite of who they were.
Has she become obsessed with her appearence. Weight loss, tanning, change in hair style. tooth whitening, plastic surgery.
MLC will generally strike a LBS out of the blue. There may be the normal marital issues but nothing major.
Have you read the resources link that I sent you on your other post yesterday?