No it won't ruin things, but it may slow your weight loss down.
However, you need to find a way to make this WOE work for you in the long term, and if this means a bottle of Prosecco on a Friday, then so be it!
I lost my weight (2 stones) from January to November. So it took me a long time. However, during that period of time, I drank (mostly white wine) every weekend and if I was going out during the week I also had a drink. I don't go out very often during the week, so when I do I don't really see why I shouldn't have a drink!
I also had a couple of weekends away with DH which were very self-indulgent, a week working in Athens, where low carbing wasn't always easy, and I had clients to be entertained as well, plus a fortnight's family holiday where I ate what I wanted.
The message here being that I stuck - overall - to low carbing, lost the weight but never felt or allowed myself to be feel or be deprived.
Doesn't sound like a 'diet', does it?!