If only you knew how much I loved you

Hi,
I'm wondering about this sentence (heard in a song):

If only you knew how much I loved you.

Can that "I loved" be present in meaning? I think it could refer to the past ("I once loved you"), but also to the present ("I love you now").
Would it be ok to say "If only you knew how much I love you"? I think there would be a difference:
If only you knew how much I loved you. (You don't know how much I love you, and I wish you knew that. Could be used in a song, for example)
If only you knew how much I love you. (I love you more than you think, I love you so much and now I'm telling you)

Any comments? Thank you in advance

Marius Hancu wrote:

Only love works IMO for present time.

I have to agree.

Is the verb "to love" an exception then? Are there other exceptions? Thanks

Thank you Jim, you saved my brain from melting.
Now, I'd like to ask a few more questions to complete this thread...

If only you knew how much I loved you.

You said that "loved" can refer to the present. Can it also refer to the past, or is it more usual to use the past perfect "had loved" in that case? Here's the sentence again:

If only you knew (=If you knew now) how much I [loved/ had loved] you. (=I once loved you, referring to the past)

It seems in sentences like that backshifting is more common than not backshifting when referring to the present ("if I knew where she lived" instead of "...she lives"), but what happens when we refer to the past? I suspect that in that case backshifting wouldn't be the common choice, for the simple reason that native speakers don't tend to use the past perfect much. Any opinions?
Thank you in advance

Eeuw!  Melted brains are so unsightly!

You said that "loved" can refer to the present. Can it also refer to the past

Yes.  There is always an end to the backshift process -- the point where you run out of tenses that refer to an even more distant point in time!  In this case I wouldn't feel comfortable going even as far as the past perfect.  If only you knew how much I had loved you is just a bit quirky, I think.  With the main clause in the past perfect, it sounds all right to me, though here the subordinate clause is not backshifted any more than in your original example.

If only you had known how much I loved you.

CJ

Note:  The word order for this expression with "know" is more likely to be If you only knew, at least where I live, at least used alone, as follows.

-- You seem tired.  Did you have a rough night?
-- If you only knew.

CJ