Why would my husband do this?

So my husband called my cousin hott, I've seen him going through her Facebook photos while he's right next to me. He's liked her pictures and normally I would just say "hey it's a picture" but given the circumstances I find it really disrespectful. This is just making me feel extremely insecure in my marriage and with myself. This has been just a reoccurring thing with him just always talking about her and one of my other cousins as well just recently as well we've spoken about it he apologizes and we make up but then this happens again. We have a daughter and I feel like this is the reason I stay. But here recently my heart just aches, I went into this marriage making him my one and only it doesn't feel reciprocated. Am I overreacting? If not what would your next steps be? I'm just emotionally tired.