One person is (S)ingle. The rest have exactly one heterosexual partner. Put one letter for relationship status (M or D) and one letter for the first letter of that person’s partner.
If Axel is married to Narda, then Narda is married to Axel.
Narda is adjacent to three females: Holly, Isla, and Tammi. No man’s name is longer than five letters, so Narda’s daughter must be Isla. The five-letter men are Caleb, Gavin, Steve, and Ulric. Axel tells you that the top row are all married, so Caleb is a husband, not a boyfriend. Axel also tells you that Isla must be with someone along the outer edge, ruling out Gavin and Steve. Therefore, Isla and Ulric are dating each other. Make sure to fill in both.
Ulric tells you that Steve is basically between Tammi and Tammi’s husband. According to Axel, Tammi’s husband must be along the outer edge, so Tammi is married to Walt.
Axel tells you that Lydia is with Gavin, Matt, Rod, or Steve. According to Walt, Lydia cannot be with Gavin or Rod. According to Isla, Lydia cannot be with Matt, so Lydia must be with Steve. Isla also tells us that Rod is dating and Tammi tells us that the fourth row has exactly two people who are dating someone, so they are Rod and Ulric. This means that Steve and Patty are either single or married. Since Lydia and Steve are together, they must be married. (Actually, given that there are 13 men and 12 women, no woman can be single)
Axel tells you that Gavin is not with Holly because she is not along the outer edge. Axel also tells you that Gavin is not with Bella or Edith because Gavin has a girlfriend, according to Steve, but Bella and Edith are wives. The remaining 5+ letter names are Patty, Violet, and Xylia. Walt tells you that Xylia is with Caleb or Matt. Patty cannot be a girlfriend because of what Tammi says, since you know from Isla that Rod is a boyfriend. Therefore Gavin and Violet are dating.
Again, Patty cannot be a girlfriend since Rod is. Xylia is with Caleb or Matt, according to Walt. Therefore, according to Isla, Rod’s girlfriend is Kyla.
Kyla tells you that either Fran or Patty is a girlfriend. Again, Patty cannot be a girlfriend (Step 6/25), so Fran must be dating Jeff, Otto, or Zack. According to Gavin, not Jeff actually. Bella and Edith you know are married from Axel. You know Xylia is with Caleb or Matt from Walt. Rod must be referring to the top two rows. It already cannot work in any of the bottom three rows. So in the second row, Holly and Jeff must be together.
To recap, Bella and Edith are married. Fran is with Otto or Zack. Holly is with Jeff. Patty is married. Xylia is with Caleb or Matt. Since Lydia tells you that Yogi is not married, he must be single. No one else can possibly be his girlfriend.
“No more than seven married couples” also means at least five dating couples. Right now there are three: Gavin+Violet, Isla+Ulric, and Kyla+Rod. You also know from Kyla that Fran is dating Otto or Zack. The top row are all married (Axel), Patty’s married (Tammi), and Matt and Xylia are married (Lydia-their only just dating options are each other, but at least one is married). So that means Holly and Jeff are dating, and you just gathered that they are together, so Holly and Jeff are dating each other.
According to Jeff, if Matt is not with Edith, then Bella is married to Otto. Matt, in turn, would be with Xylia. If Matt is with Edith, then Xylia would be with Caleb, according to Walt. And if Xylia is with Caleb, according to Holly, Otto would be married. So Matt is either with Edith or not with Edith. Either way, Otto ends up married. This means Kyla must be referring to Fran+Zack as dating.
You just established that Otto is definitely married, so according to Fran, Bella is not with Dirk. Bella cannot be with Caleb because that would mean Matt+Xylia and then neither of Jeff’s options would be true. Bella also cannot be with Matt because then Matt can’t be with Edith and Bella can’t be with Otto, so again neither of Jeff’s options would be true. So Bella must be with Otto, and you know from Axel that they are married.
According to Jeff, Matt and Edith are not together. So then, according to Isla, Matt is with Xylia. Since at least one must be married (Lydia), they must be married to each other.
Steve is adjacent to his wife Lydia. Axel tells you that the top row are all married. Therefore Dirk and Edith are not together. This means Caleb is married to Edith and Dirk is married to Patty.