In addition to what everyone else is saying, keep in mind muscle imbalances can cause this type of issue and they are very, very common - especially in sports (to include martial arts training) since almost all of them require repetitive motion which overstimulates certain muscles compared to others.
In my case, I was struggling with stretches that involved mobility on my outer thigh and doing yoga/stretching the hell out of it was providing marginal help at best. This got me thinking about muscle imbalances and how a lot of guys have super tight pecs and anterior delts as a result of doing way too many pushups and bench presses and nowhere near enough rear delt and mid trap work, resulting in everything being pulled forward and limited mobility. Stretching the anterior delts everyday may help a little bit but it's not going to solve the actual problem, the problem is they're overpowering their antagonist muscles by such a wide margin that they're pulling the structure off balance, thus the answer is that the antagonist muscles - in this case the posterior deltoid and mid trapezius - need a lot of work.
Applied to my outer thigh/abductor issue, I realized that for the better part of a decade I have been squatting with a narrow stance which targets the outer thigh, which is a good thing, but I have done zero inner thigh work, and when I tested the strength of my adductors (things like sumo squats, pulling the leg across the mid-line of the body, diagonal lunges, etc) I found out real quick that I was comparatively very weak at these movements relative to anything which targets the outer thigh. When I started squatting with a wider-than-shoulder-width stance with my toes pointed somewhat outward and my knees extending out and away from me at a bit of an angle, and a couple of sets of adduction after squatting, doing this in addition to yoga helped me to gradually begin seeing improvement.
If you can, see a physical therapist and get tested for these types of imbalances - or any others involving the hip/groin. For the adductor/abductor issue I think a very simple test that can immediately tell you that you have an imbalance (though passing the test is not conclusive that no such imbalance exists) is how you walk - if your feet naturally take more weight inward than outward or vice versa it means there is an imbalance.
The guy who suggested the frog stretch might not be a bad thing to try - if groin-specific tightness is what's inhibiting you in the butterfly stretch then this might be able to help a bit, as well as other groin specific stretches you can find.
