Just looking at tents again.

These are the leading contenders for lightweight tents for a thru-hiking couple:
- Copper Spur….| 28 ^2 feet | 3lb 1 oz | $500*
- Duplex…………..| 28 ^2 feet | 18.5 oz. | $669
- X-Mid Pro 2 …| 30 ^2 feet | 19.6 oz. | $679*
- Duo Off Set……| 31 ^2 feet | 19.7 oz | $769
- Dipole li 2……..|32.25^2 feet|24.7 oz | $799
- Triplex …………| 37.5 ^2 feet| 21.6 oz | $749*
For Triplex add weight of pole cups for .28 ounces for two. * for tents we own.

Out of range are the Double Rainbow Li (28.6 oz and 30.6 ^2 feet at $724. Optional double wall). HMG’s tents are either too small/heavy or have the support pole in the middle. Fine for two people but not for a couple.

Copper Spur included because five years ago it was the baseline highest rated tent in several surveys. Picture is of ours set up on a platform.
Tents announced but not yet out are the XMid Pro 2p+ (a larger Dyneema XMid) and the Offset Triplex.
Too fragile is the Dyneema Big Agnes Tiger Wall at $1,799.95 —a perfect storm of too small (27 ^2 feet), too fragile and too expensive and at 1.7 pounds it is also close to too heavy. https://www.backcountry.com/big-agnes-tiger-wall-2-carbon-tent-2-person-3-season
I’ll note I’ve seen couples quite happy on long trails with the Copper Spur 3p (the size larger than we own with 41 square feet vs 28 square feet of space for the 2p) MSR tents (3p at 39 ^2 feet) and a huge variety of other tents. Comparison of 3p tents.

Space is very personal as to how much people need. There are couples who thru-hike with a single shared 1 person tent. ?♂️
Most find the standard 2p sizes ok for a weekend or maybe a week but too small for longer until you get past the 26 to 28 square foot range towards 30 to 32 square feet.
Update.
Offset Trio just released.
https://zpacks.com/products/offset-trio-tent
41.9 ^2 feet. 22.9 ounces. $869.00.