I remember reading a novel where multiple timelines converge over several days and then separate again. The character gradually becomes aware that the convergence is happening through a sequence of events (which I can't now recall).
In one scene, the lead character sees his own body (from another timeline) in the burnt-out, melted remains of his yacht. The action takes place in a coastal town with a harbour (hence the yacht). As far as I can recall this was not a time travel story.
He is re-united with his dead wife/lover but at the end
the timelines separate again and he loses her and ends up with someone else.
I think I read this in the 1980s, I thought it was by someone like Bob Shaw, Roger Zelazny or Keith Laumer, and may have been a yellow Gollancz hardback. However I haven't had any luck finding it!