Bfs sister hates me?

Myself and my partner have been together for 4 months so far. We're getting on amazingly, and I couldn't be happier.. there's just one problem, his sister. The first time I met her, she totally blanked me, and said meeting me isn't important atm, she didn't even look at me. Every time we've exchanged texts (for whatever reason), she's always been so blunt. She's recently had a baby, and I wished her well for the birth when she was going in for her elective c section, then a further text to congratulate her.. Guess what? No reply to either texts. When I was dropping off my partner to his house (lives with his sister), he asked if I could pop in to see the little one, and of course, she said no, not right now. I'm started to get extremely upset and hurt as I've done nothing wrong but actually love and protect his brother. I can't shake it out of my head that she literally hates my guts without even bothering to get to know me. My exes family didn't bother, and I don't want it to happen again with my current partner. What shall I do? Leave it, and have nothing to do with her, or text her to ask why she's not wanting to get to know me? My partner keeps telling me to give her a couple of months, yet he has said this from the VERY start of our relationship, we're now 4 months in, and she's wanting "more time".. I'm so officially done, and wouldn't even want her at our wedding (if we ever get married of course).

Bfs sister hates me?
Post Opinion