I don't think it feels like the end yet. If it was the end there would be no more screentime for the story at all or no more mentions of Rebecca. Try to look at it from the other side. If you were a shipper of TriMa wouldn't you HATE the thought that Rebecca might be sewing the dress Marlene gets married in, considering Marlene and Rebecca have wedding dress history and what always happened when Marlene and Rebecca had fittings?
I think it's kinda soap law or at least VL law that it has to always be darkest before the light. And VL kinda has a history of these long drawn out romances (people call them Kaugummi/bubble gum because they draaaaaaaaaaaaaaag).
For example, last year there was a story about a woman who was married with a grown up son who was in love with the twin brother who was also a priest (yes I realize that sounds like a joke, but that's VL for you). The brother came to town for another unrelated reason, they tried to avoid each other forever (=Rebecca trying to hide her feelings for Marlene before the spin the bottle night), then they swore up and down that rather than acting on their feelings they would try to learn to interact as normal brother and sister (= Marbecca going back and forth on insisting that they want to save their friendship), roughly every 3 weeks or so the woman tried to blackmail her brother into leaving the island, she constantly lied to her husband about every tiny little thing pertaining to her brother (first that he was her brother, then how they were separated, then that they used to be in love, then that she loves him, etc), she dreamt of her brother while lying in bed with her husband, she vowed to stay away from him even after her husband had found out the truth and dumped her. And then just as the brother was about to leave the island for good the woman nearly killed herself, her son gave her his blessing, she ran after her brother and they lived happily ever after/are one of the biggest supercouples of VL. I believe it's called a "5 minutes before closing time" ending
[youtube]http://www.youtube.com/watch?v=BAe-C263BN4[/youtube]
Dana and Hagen also had a long phase where she pushed him away over and over again and tried to fight for Marlene instead. Same goes for many other couples.
Again I'm not saying it's impossible, like that the ending of Marbecca will be Rebecca sewing Marlene's wedding dress and both of them finding peace through that/laying their relationship to rest through that (after all there was a head writer change in the middle of Marbecca and new writers might always have different goals). But I also think that the current Marbecca happenings still don't really violate the VL typical couple structure (even if that structure is really frustrating and annoying).