Surely a lot of art is in some way about love? Either feeling it, losing it, seeing it through others eyes?
I would say all the religous works depicting Christ & the Madonna are strictly about love - even if it is love of religion or church or of an icon.
Maybe all you need to get an answer to this is to look at some artwork & see how someone felt love when they were creating it!

Dante Gabriel Rossetti -The wedding of St George and Princess Sabra. John Everett Millais- The Black Brunswicker and The Huguenot.

LOVE, by artist Robert Indiana.
http://www.artcyclopedia.com/feature-2004-09-indiana-LOVE.html
http://moma.org/collection/browse_results.php?criteria=O%3AAD%3AE%3A2812&page_number=3&template_id=1&sort_order=1
Belle Dame Sans Merci - Sir Francis Dicksee
http://www.allposters.com/-sp/Belle-Dame-Sans-Merci-Posters_i150967_.htm
Many by Chagall
The Wedding :http://www.richardandmimi.com/chagall.jpg
Amoreux de Vence:http://www.allposters.com/gallery.asp?startat=/getposter.asp&APNum=314294&CID=6184915B8F8D4FE49FECF186F889BAB0&PPID=1&search=chagall&f=c&FindID=23223&P=1&PP=8&sortby=PD&cname=Marc+Chagall&SearchID=
http://www.allposters.com/gallery.asp?startat=/getposter.asp&APNum=324823&CID=6184915B8F8D4FE49FECF186F889BAB0&PPID=1&search=chagall&f=c&FindID=23223&P=1&PP=8&sortby=PD&cname=Marc+Chagall&SearchID=
http://www.zchor.org/index_files/5766.JPG
http://ideiascomimagem.no.sapo.pt/tounalua/125_amoresexo1_labranche.jpg
http://images.google.com/imgres?imgurl=http://www.chagallpaintings.org/images/Lovers-in-Moonlight.jpg&imgrefurl=http://www.chagallpaintings.org/loversinmoonlight.html&h=332&w=250&sz=9&hl=en&start=29&um=1&tbnid=N8QweTxnH_QnLM:&tbnh=119&tbnw=90&prev=/images%3Fq%3D%2Bpaintings%2Blovers%26start%3D20%26ndsp%3D20%26svnum%3D10%26um%3D1%26hl%3Den%26sa%3DN%26ie%3DUTF-8%26oe%3DISO-8859-1
The Lovers - Picasso
http://www.art.com/asp/sp-asp/_/PD--10085403/SP--A/IGID--857693/Masterworks_of_Art_The_Lovers.htm?sOrig=CAT&sOrigID=1949&ui=228843323E6B4264980E881F15D47C81
Jan Van Eyck's "Giovanni Arnolfini and His Bride" (wedding portrait)http://www.allposters.com/gallery.asp?startat=/getposter.asp&APNum=290475&CID=6184915B8F8D4FE49FECF186F889BAB0&PPID=1&search=van%20eyck&f=t&FindID=0&P=1&PP=4&sortby=RD&cname=&SearchID=
Renoirance at Bougival
http://www.hlla.com/covers/renoir.jpg
http://www.renoir.org.yu/gallery.asp?id=31
Van Gogh: A Pair of Lovers in Arles:
http://images.google.com/imgres?imgurl=http://www.vggallery.com/painting/f_0544.jpg&imgrefurl=http://www.vggallery.com/painting/p_0544.htm&h=595&w=410&sz=36&hl=en&start=20&um=1&tbnid=5lpggG07I47LbM:&tbnh=135&tbnw=93&prev=/images%3Fq%3D%2Bpaintings%2Blovers%26svnum%3D10%26um%3D1%26hl%3Den%26ie%3DUTF-8%26oe%3DISO-8859-1
Mary Cassatt - Mother and Child http://www.allposters.com/gallery.asp?startat=/getposter.asp&APNum=1000038&CID=6184915B8F8D4FE49FECF186F889BAB0&PPID=1&search=cassatt&f=t&FindID=0&P=1&PP=5&sortby=RD&cname=&SearchID=
The Sarcophagus of the Spouses - In Cerveteri in Tuscany, Italy (ancient Caere in Etruria) and dating about 520 BCE.
http://www.ancientworlds.net/aw/Post/467810
The Lovers - Mel Williams
http://www.magnetictimes.com/index.php?cID=115&pic=3246