Personally, I would just pretend it never happened.

From UA's point of view, (as kmersh) said, a PDA like this from an employee in uniform is likely a really big deal. And it should be; when you operate potentially-deadly heavy equipment and you are a customer-oriented business, you've gotta take professionalism very seriously. For this reason, I suspect that if you send in pictures of the incident, the FA in question is going to suffer real consequences.

But it just feels to me like the OP should let it be. I wouldn't want to be the one who gets a UA employee fired just because he was overly excited he got his boyfriend or husband a J seat. As a passenger, I don't feel too compelled to do UA's work for it and keep its FAs in line (the crew should be doing that). I just don't care about UA enough to help them out at a real cost to myself---the cost is feeling bad that maybe I got someone fired.

Plus, it's not like there was a real injury suffered on the part of the OP, other than annoyance at the level of service---and let's face it, if you fly commercial in 2018, you are going to be annoyed with the level of service for one reason or another.