Well, "There are other fish in the sea" is a possibility, even though the implication may be that of a relationship, it doesn't have to be.

You could also stick with the feline reference with:
There's more than one way to scare a cat

Also:

There's more than one way to eat a pie.
There's more than one way to crack an egg.
There's more than one way to beat an egg.

Of course, you could always fall back on the always witty:
That's not the only way.
There's more than one way to do that.
or
There's a better way.

"There are other fish in the sea" is a possibility. Even though the implication may be that of a relationship, it doesn't have to be.

You could also stick with the feline reference with:

There's more than one way to scare a cat.

Also:

There's more than one way to eat a pie.
There's more than one way to crack an egg.
There's more than one way to beat an egg.

Of course, you could always fall back on the always witty:

That's not the only way.
There's more than one way to do that.
There's a better way.