How do I get out of going to the bar with someone without them hating me?

After many, many months of turning down my sister in law for a drink, I finally caved and said yes just this one time. While at this bar I ran into a good friend/cousin. I always turn her down when she wants me to go out with her too. She kept insisting that in the next few weekends that I have to go out with her cause I never do. How can I politely get out of this? I don’t like to go to bars it’s just not my scene and I don’t find enjoyment there. All they ever want to do is bar hop so asking her to do something else wouldn’t work. TIA.