Here are a few I like. The last is maybe not a traditional "love poem" but it's about love.

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When you go by Edwin Morgan

When you go,
if you go,
And I should want to die,
there's nothing I'd be saved by
more than the time
you fell asleep in my arms
in a trust so gentle
I let the darkening room
drink up the evening, till
rest, or the new rain
lightly roused you awake.
I asked if you heard the rain in your dream
and half dreaming still you only said, I love you.

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Bookworm by Norman MacCaig

I open the second volume
of a rose
and find it says, word for word,
the same as the first one.

The waves of the sea
annoy me, they bore me;
why aren't they divided
in paragraphs?

I look at the night
and make nothing of it -
those black pages
with no print.

But I love the gothic script
of pinetrees and
on the pond the light's
fancy italics.

And the cherry tree's petals -
they make
a sweet lyric, I appreciate
their dying fall.

But it's strange, girl, how I come back
from the library of everything
to stare and stare
at the closed book of you.

When will you open to me
and show me the meaning of all
the hard words
in the lexicon of love?

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An Arundel Tomb by Philip Larkin

Side by side, their faces blurred,
The earl and countess lie in stone,
Their proper habits vaguely shown
As jointed armour, stiffened pleat,
And that faint hint of the absurd -
The little dogs under their feet.

Such plainess of the pre-baroque
Hardly involves the eye, until
It meets his left hand gauntlet, still
Clasped empty in the other; and
One sees, with sharp tender shock,
His hand withdrawn, holding her hand.

They would not think to lie so long.
Such faithfulness in effigy
Was just a detail friends could see:
A sculptor's sweet comissioned grace
Thrown off in helping to prolong
The Latin names around the base.

They would not guess how early in
Their supine stationary voyage
Their air would change to soundless damage,
Turn the old tenantry away;
How soon succeeding eyes begin
To look, not read. Rigidly they

Persisted, linked, through lengths and breadths
Of time. Snow fell, undated. Light
Each summer thronged the grass. A bright
Litter of birdcalls strewed the same
Bone-riddled ground. And up the paths
The endless altered people came,

Washing at their identity.
Now, helpless in the hollow of
An unarmorial age, a trough
Of smoke in slow suspended skeins
Above their scrap of history,
Only an attitude remains:

Time has transfigured them into
Untruth. The stone fidelity
They hardly meant has come to be
Their final blazon, and to prove
Our almost-instinct almost true:
What will survive of us is love.