One Alone Cannot Make Two

One alone cannot make two,
But two alone can tally three.
If some find sums enough to do,
Some find some their ecstasy.

Yet do not add unless you love,
For greater sums require more,
And though in proof might pleasant prove,
In life might prove a lifelong chore.

Valentines ought best beware
Of multiplying much too soon.
While two might err, far more must bear
What didn't add up one afternoon.