In her support with Catherine she's coming back from a mission and Catherine is the one who said she was worried she wasn't going to come back with Shamir being surprised Then Shamir says "we can wed if you're that worried about losing me" because Catherine is the one being so concerned so she wanted to crack a joke
Shamir constantly has a dry sense of humor where she often has to clarify she's making a joke, it comes up in lots of her supports
In her Balthus support in Warriors the whole conversation starts because Balthus wants to talk about how similar they are but Shamirs whole point is that they aren't
Balthus says they both are great fighters but Shamir says they have different styles, they both drink but Shamir says she can hold her liquor. They gamble but Shamir doesn't lose all her money.
Shamirs "I doubt our tastes are similar" is just a continuation and the fact that he's bringing up all these things so she jokes that the next thing they should talk about is women
Shamirs endings with Byleth, Dedue, and Hubert explicitly mention marriage
Her endings with Claude, Ignatz, Cyril, don't mention marriage
Catherine doesn't mention marriage
frogs les endings have marriage
If they were gonna make her gay they would have
Catherine is the one who blushes when Shamir mentions that Dagdans marry whoever
Shamir has a deadpan sense of humor, as seen in that Catherine/Balthus
Shamir tells Shez and Leonie that you shouldn't force your own preferences onto others
Shamir has no S rank with female Byleth but will blush with MByleth just from holding hands, but not with Catherine.
Their ending continues to paint them as partners, not a married couple, when some of Shamir's other paired endings do state marriage
The unit and tt imply it's just a vacation for Shamir and she wants alone time by herself, even pointing out her and Catherine are only work partners
Shamir has a penchant for sarcasm, unless you think she enjoys punching nobles or making parents fight