Anal [f]un with [m]y girlfriend

First time poster, long time lurker. Apologies in advance for typos as I'm typing on my phone at work. Apologies if this is long.

Anyway, a little background. I've been with my gf for almost 4 years now and we have a great sex life. She's about 5'2" with a gymnast build, has amazing D cups and an ass you could stare at for days. I'm a 5'9" with a muscular build, 6.5 inches cut with good girth. We have done anal a few times before and she loves to be fingered while I go down on her but this is the kinkiest anal experience we've had to date.

We've been going through a bit of a dry spell lately. We went from having sex 4-5 times a week to maybe 1 time every 2 weeks. Until one night last week.

It was a normal Thursday night and we had just finished cleaning the kitchen after dinner. I had been lurking on Reddit all week and was pretty horny from not indulging myself. She had worked out right before dinner so she stepped into the shower after we were done with the dishes. I'm sitting on the couch which looks right toward the bathroom mirror in our small downtown apartment.