"They are still good friends," a source told the site. "The relationship just ran its course."
The other evidence of their split: They haven't been in public together since December, and they have stopped featuring each other in their Instagram posts.
This sad news comes on the same day that TVD is ending its eight-season run with a one-hour special at 8 p.m. EST and the series finale at 9 p.m. Tonkin and Wesley met on the set of TVD in 2012, when she played werewolf Hayley Marshall. At the time, Wesley was still married to Pretty Little Liars star Torrey DeVitto. DeVitto and Wesley announced their divorce in July 2013. By that fall, Tonkin and Wesley were spotted out together, and they've been an item ever since.
Oddly enough, Tonkin's Hayley and Wesley's Stefan Salvatore didn't have a scene together until last year's crossover episode between TVD and its spin-off, The Originals.
"I had never worked with her before," Wesley told Entertainment Tonight of the episode. "It was very funny, we talked about it, but we literally never rehearsed [the scene] or ran it. We just said, 'Let's just do it when we get to set,' because otherwise it would just be awkward, and it was cool. It actually wasn't in the least bit uncomfortable or awkward. It was just kind of like we just did it and we were both in it and we both committed to it. It was nice, it was funny."