Learn English – ‘lose your money’ or ‘lose money for you’

Those who come across this question might find helpful this article in the NY Times.

The origin, as dozens of other Lexicographic Irregulars stepped forward to say, is British, probably Cockney. The first time the saying saw print was in an 1846 Punch. A cartoon entitled ''The Ministerial Crisis'' has a showman telling a customer, ''Which ever you please, my little dear. You pays your money, and you takes your choice.''

The phrase still means ''The right of choice is to the buyer,'' or a more sophisticated ''Power belongs to those who have paid their dues,'' but a much different sense has emerged. ''The phrase is used today,'' writes Edward C. Stephens, dean of Syracuse University's Newhouse School of Public Communications, ''not so much as an invitation to choice as it is a rejoinder to complaint. It seems to be similar in intent to 'You made your bed, now lie in it.' Another variant is 'Look, if you don't like it, you can just lump it.' ''

However in this particular context, I would argue that it's a gambling reference -- you don't know the outcome until you roll the dice. It might work, it might not. You won't know until you make your bet and make a choice.

The author is referring to the energy, vigor, or vitality of a relationship as its

juice

by ending a relationship, the relationship will "lose its juice".

"Juice" is also AmE slang for electricity, a form of energy.

In the 1970's, because of his running ability at USC and Buffalo, OJ Simpson was called
"The Juice" as a play on words, OJ (orange juice), and a nod to his prowess.

The Juice is loose