Sounds like you're right, they are "fighting" each other. I had some major flexibility issues back in the TKD days. It is doable to get over/around/through them, but it's not fun and it's definitely not fast. Harder too, as you're experiencing, increasing your flexibility when older.
Tons of good books out there on the subject, the one I've always preferred and referred others towards was Bill "Superfoot" Wallace's book, Dynamic Stretching & Kicking. I've no idea if you can lay hands/eyes on a copy, but there's tons of good info out there.
List of the Best Stretching & Flexibility Books - Black Belt Wiki
The thing that I personally did which made the most difference in lateral hip flexibility was... watch TV in a stretched position. I'd just sit on the floor, in as much of a V-sit as I could manage (in the beginning not much), and slowly, over days and weeks, my feet (straight legs and trying (key word, trying) not to have any tension other than the stretching tension being in my leg muscles... slowly move my feet apart. It became a habit, and I'd end up sitting that way, studying, etc. Took a couple years but I got to a full ide split and to about 4, maybe 6 inches from the full middle split.
But, you may not want to even put out that effort and time-demand. I put it away myself about 15 years ago. I "can" still do head kicks, but I don't really want or need to.