i don't know

I feel like my so is to close to his sister in law. his brother has been with this girl for like two years they just got married last month i like her she's nice but he will sit there in front of everyone laughing and talking to her and if I try to talk to him he ignores me we saw her one day in town and he texted her saying he saw her and they carried a conversation for a good while when he's on break at work he talks to her if he sees her and today's her birthday and he made sure he posted on her Facebook wall and saying he hopes she has a good day.. when it was my birthday he didnt say anything on Facebook he texted me and thats it i guess I'm just going crazy but he seems to close to her.. please no rude comments I'm just curious if anyone else has had this happen.