a one-night stand is like a stage 0 relationship. it is and is not a romance at the same time. treatment isn't necessary, nor is any kind of excision. keep an eye on it, you're prone to more advanced relationships, but statistically it probably won't happen until you're out of your 30's, at least.
a stage 1 relationship is what's commonly referred to as a "scare". you suddenly comprehend your own mortality, a tremendous panic ensues. It's at this point that your shittiest friends will give you up for dead, exhibiting their ignorance of the high probability that you will soon have a clean bill of health and be relationship-free. at this stage, treatment is remarkably simple: separate the problem from your body and move on with your life.
when relationships reach stage 2 things get thorny. no longer merely a sinister lump, the malady has begun to spread through your system, and though it has yet to find additional footholds, if not caught soon, it will continue taking over your body until it kills you. treatment at this stage becomes complicated and painful, as the excision is followed by ingesting horrible poisons regularly for six to eight months and a near total transformation of your self-image, almost always for the worse. here, also, you become terrified of a recurrence, which, though unlikely, is entirely possible.
at stage 3 the original relationship, once too small to notice, has grown to an immense size. you will finally begin to exhibit symptoms, though it will be little more than unusually strong fatigue, which makes it rather hard to self-diagnose. the spread through your system continues, and while the disease still has not found an additional home, you are now quite likely to die from it, sooner or later. by now treatment is truly a horror, as you begin first with the ingestion of horrible poisons for an indeterminate amount of time, attacking the disease from the edges and whittling it down until ideally, one day, the thing is small enough to simply cut it out. there is an extremely high risk of recurrence in these situations.
finally, a stage 4 relationship will almost certainly kill you. the disease has taken up residence all over your body, including in places without the use of which you would not be able to live. your chances of ever again being without it are essentially zilch. though a cure is more or less impossible, we are much better at buying you time than we were even a decade ago. by wildly messing with your body's hormone levels and more or less obliterating whatever sense of sexuality you may have had left, you can be kept alive for many many years (as noted, however, you and the disease are essentially inseparable). these days, some patients survive with stage 4 relationships for 20 or 30 years.
eventually, though, it spreads to your liver and/or your brain. that's when you're truly fucked.