The purpose of "such" words is simple: it's to remind readers that yes, it might be a relationship, but it's a BUSINESS relationship if you're paying for sex. BOTTOM LINE, it's BUSINESS. Put another way, you're not paying for sex, you're paying her to leave. Which I have no trouble with because I'm NOT promising a future that I can't deliver, and neither is she. We have fun, perhaps some mutual enjoyment, but as I leave, I hand her cash; it's respect.
Not saying you can't have a personal relationship, I've known several that would make great partners in life's trenches. They didn't run away from hardship but did what they had to do to provide for their family. If you're ever considered family, then you're set. Just make sure she sees you as family and not as an ATM.
And you might want to be careful about using terms like "until the end of time". You've never heard Meatloaf's Paradise by the Dashboard Light, the closing?
I started swearing to my god and on my mother's grave
That I would love you to the end of time
I swore that I would love you to the end of time!
So now I'm praying for the end of time
To hurry up and arrive
'Cause if I gotta spend another minute with you
I don't think that I can really survive
I'll never break my promise or forget my vow
But God only knows what I can do right now
I'm praying for the end of time
It's all that I can do
Praying for the end of time,
So I can end my time with you!
https://www.google.com/search?q=para...d+light+lyrics