It sounds like you have identified a general need - some kind of mobility work - and you’re sorting through what the options are (yoga classes, foam rolling, you could also check out mobilitywod.com or Joe DeFranco’s Agile 8 and Limber 11 for some other at-home options).
I know that foam rolling and yoga are really two different things, but they both sorta fall under the broad umbrella of “preventive and/or rehabilitative work” in my book. I’ve never been a massage guy myself, but I know some people love them (my mother, who was mostly a “walker” for exercise but has become an avid hot-yoga practitioner in the last two-plus years, gets a massage every few weeks from a woman at their hometown yoga studio and loves it) and if you feel like it’s doing you some good, by all means keep grabbing those value slots whenever possible.
At this stage, I don’t think the EXACT choice is crucial so much as picking one or two things you can/will do and sticking to them. Maybe that means foam rolling and stretching for a dedicated 15 minutes after every lifting workout, or maybe having a separate “day” (i.e. yoga class) devoted to mobility works better.
I’ve always been lazy about mobility stuff, so I think going to a yoga class and devoting an entire session to it works best for me. If I tell myself “I’ll just foam roll and stretch after lifting” - it is too easy to finish my lift and decide “Nah, I’m hungry now, I’ll stretch later” - but if I’m at a yoga class, that’s not really an option!
One other angle worth discussing here (and it’s fine if you’d prefer not to discuss this in a public forum) is the effect that family, friends, and a significant other can have on training and a healthy lifestyle.
As I’ve alluded to in this thread, my mother and father both have taken up hot yoga since I started (it was 4 years ago for me; a studio opened in my hometown about 2 years ago, where my parents still reside, and they immediately became regulars once they tried it out). Any time that I visit home for a weekend, I know that they’ll be game to join me for at least one class.
I met my girlfriend at the yoga studio, so that’s been part of our ‘relationship’ since before we were dating…but it is still really nice to know that we can go to class and work out “together” several times each week, although we do have our “unique” fitness interests (lifting for me, Zumba for her, and we both like to run).
Point of all that being, it’s great that your GF has found a way to support your healthy habits by “sneaking” you into those open massage slots when possible, and while she may not care to join you in the powerlifting arena, there may be ways in which you can share some of your interests in “wellness” too.
Far be it from me to tell you and/or your GF how to live, but perhaps since you’ve identified this desire for some healing & flexibility on top of your PLing, if she expresses any interest in yoga as well, you might consider going to an occasional yoga class together.
I do like yoga would likely go at least once every week or so regardless, but I will say that having family and my GF also practicing yoga motivates me to stay “on my game” and go at least 2-3 times per week, or find a way to incorporate a class into family vacations, etc.