There are lots of studies on marriage, including Christian Marriage. Here are several to get you started!

1. The Art Of Marriage (Focus On Family) – study kit
2. The Meaning Of Marriage – also has a dvd & study guide (Tim Keller) *probably a little deep but definitely readable.
3. Sacred Marriage: What If God Designed Marriage To Make Us Holy More Than Happy (Gary Thomas) – also has a participant guide and dvd 
4. Cherish: One Word That Changes Everything In Marriage – also has a participant guide and dvd and a free study guide (Gary Thomas)
5. Marriage: 6 Gospel Commitments Every Couple Needs To Make (Paul Tripp)
6. You And Me Forever: Marriage In Light Of Eternity – also has a participant guide (Francis & Lisa Chan)
7. Kingdom Marriage (Tony Evans)
8. When Sinners Say I Do – also has a study guide (Dave Harvey)
9. Peacemaking For Families also has a free study guide (Ken Sande) 
10. Love And Respect AND The Language Of Love and Respect – also has workbooks (Emmerson Eggerichs)
11. The Love Dare (Kendrick Brothers) *not so much of a study as an experience
12. This Momentary Marriage  – also free download (John Piper) 
13. God, Marriage, and Family (Kostenberger) *probably deeper read though not difficult
14. God And Family Matters study guide (pd)
15. Cherish Family 2019 audio sermon series (pd)