I usually read sideways cards as having both meanings, not just upright or reversed but kind of both at once.
Since your Ten of Cups is on its side, maybe it’s showing the good parts of having emotional satisfaction but also how hard it can be to keep that going? I’d like to know what other people do with sideways cards though, I always find them confusing.
When my cards land sideways during shuffling (happens way too often), I just turn them right-side up and keep going.
I don’t really assign special meanings to them. Like if the Ten of Cups falls out sideways, I just fix it and continue with the reading.
Sideways cards remind me of that Spider-Man meme where he’s crawling on the wall, different angle, same hero!
With tens being completion cards, maybe your Ten of Cups is showing you that happily-ever-after doesn’t always look like the fairy tale ending. Could be worth checking what house/position it landed in. A sideways outcome card means something else than a sideways situation card.
I had a sideways Ten of Cups show up in a relationship check-in. Read it as not quite there yet, not blocked, but not fully arrived either. I pulled two more cards to see what would help and what would hurt. Got 4 of Wands for what would help and 5 of Swords for what would mess things up. Pretty clear message, celebrations and rituals would help, but keeping score during arguments would tank everything.
We decided on weekly dinners with phones off and agreed to drop the sarcasm when we fight. Next month the Ten showed up upright.
When the Ten of Cups lands sideways, I look at the tilt.
If it leans left, I take it as a cue to bring some logic and practical steps to what ‘emotional fulfillment’ means for you. If it leans right, I read it as letting go a bit and letting the feelings lead.