I give you a CD from our past so you can listen to our love back then.

guoqude = bygone; in the past

na shi = that time = back then.

ting ting = listen => recall or remember (our love back then)?

Perhaps the CD has an old love song that they used to both listen to whenever they made love.

Perhaps the CD is a recording of their love-making?  I doubt he would have done this on a CD though.