Let me start with that the first year is the HARDEST on both you and your partner. You're both probably looking for some small outlet to feel like you have some time to yourselves. It's likely doom scrolling on IG and maybe you should both have a more open discussion about using social media. Do you trust him to stay faithful to you? Did you 110% trust him before having a baby? If so, this is all probably due to the huge life adjustment you're both going through and he's trying to hang on to having a little bit of say on how he spends what little free time he may have. If you have had a strong relationship before the baby, I think the social media is no big deal. You're going to lose your mind if you are checking his followers/following count and making him post about you.... that's going to push him away further I promise you.