Our marriage has entered its 7th year, and lately my spouse is constantly adding new people on social media. It doesn’t matter whether they are men or women, but I’m particularly uncomfortable with them reconnecting with old female friends. At first, I didn’t pay much attention to it, but now small arguments have started to arise. Is it indifference, a habit, or something completely different? Could you share your thoughts?
How long has it been like this? For example, did it suddenly start just 7 years ago, or has it always been there but you didn’t notice? Maybe they entered a new environment and started feeling lonely. They might be using social media a bit for this purpose too 
I think the main issue here is her adding her old female friends. Sure, everyone adds a few people from the past occasionally, but it’s strange for it to be a constant thing. You might want to ask if she talks to them or if she just adds them and leaves it.
Honestly, I can’t help but ask this: how many times have you talked to your partner about this properly? Maybe they haven’t even been able to express themselves. If you’re feeling tense and seeing it as jealousy, they might just brush it off thinking, ‘what’s the big deal?’ Unfortunately, these kinds of issues grow out of a lack of dialogue.
You may have an unnamed boundary issue. If there’s no specific agreement among you for social media, it’s natural to have different limits. Discussion won’t provide a real solution. Instead, make a concrete arrangement, like being transparent with each other about friend additions. You can draw a small boundary.
Reading the comments, I realized that I actually haven’t talked about this issue very directly and calmly. I expressed it more during the discussion. Generally, he says that he doesn’t talk to them, but I don’t understand that desire to add. Today, I will seriously sit down and ask openly, let’s see what he will say.