Hello, Emmie. I've been thinking about your request for 24 hours now.

There just aren't many old songs about true love in the abstract. I would say that there are far more old songs about love gone wrong than about successful loves.

And the songs that are about happy true love tend to be individualized. For example: Annie Laurie. Annie is a certain person and she lives in a certain place - Maxwellton. Other examples:

Rose of Tralee
Rose of Allandale
Bonnie Eloise, the Pride of the Mohawk Vale

See what I mean? I think that generalized love songs which can apply to anybody are a modern phenomenon.

Meanwhile, Valentine's Day is only 3 days away. If you are doing a show, I think your best bet would be to visit your public library and get lyrics, chords and music from books in one step.

One possible source - love songs of Robert Burns, such as "My Love is Like a Red, Red Rose."

Another idea is Tin Pan Alley songs from approx 1890 to 1920. They would be public domain, and you can probably find tunes you know already. such as Bicycle Built for Two, The Band Played On, Smile Awhile, And Let the Rest of the World Go By.