are right, when crossing those boundaries both of them should be responsible for going with the relation up or down. the failure of that relation would be the responsibility of both of them especially if they want it and never work on it. If someone really wants it while the other is not, then it would be the fault of the last one.

Working on making this relation a success would never work from one side. Both have to participate and find different ways to make it work, if they really want it. Otherwise it would be better for them to quit it before it cause more pain for both of them later, the more they stay with each other knowing that it won't work ... the more painful later it would be when they get separated later.