Another way to say "the end of our relationship."

Both are rather awkward and strange-sounding. Probably the most common way to end a relationship, at least in America, would be to say: "We need to talk ..."

“I think this is over.”

“I think things are over between us.”

“I don’t think this is going to last much longer.”

“It’s getting close to the end of things between us.”

“It’s getting close to the end of our time together.”

Now I’m going down to my basement to listen to some Leonard Cohen and paint the walls black…

Putting us in quotes might help. That way, both sentences could work.

Instead of "relationship", you could say; this is the end of our . . .

liaison.

affiliation.

connection.

partnership.

alliance.

friendship.