The white VT looks to be almost constantly submitting to the CT male. Even though there is no actual physical violence, that kind of conflict can still be extremely stressful for fish, particularly the submissive one.
Also, it may be that one day the balance of power shifts and the white VT decides not to submit to the CT. Then you could very well end up with a maimed or dead fish.
Bettas are surprisingly unpredictable. Signs of aggression can be extremely subtle. Having wild betta males that share a tank, sometimes all it takes is a hard look from a dominant fish and the weaker one will stripe up and retreat.
It is very easy to miss warning signs, and this can lead to disaster.