If you want something solid to start with, try the Cross and Triangle, aka the Celtic Cross. It’s a 10-card layout that gives insight into both you and your partner — how you interact, and what each of you needs and expects around the relationship and sexual intimacy. I usually find it useful for general relationship advice too.
Another good one is the Relationship Hexagram. Seven cards, and it’s great for seeing how a relationship is progressing or where it could be improved. It’s especially handy when you’re working through conflicts or recurring issues between two people.
There’s also a Seven of Cups spread that people use to explore feelings in a relationship. It’s helpful if you want to get a sense of how one or both partners are experiencing the current situation.
Finally, the Lover’s Triangle is worth trying for compatibility stuff. It’s a nine-card spread aimed at mapping feelings, desires, and the potential for the relationship to work out.
Bottom line: pick the spread that feels right for the question you have. Try a few and see which one gives you the clearest answers.