Hia! to the wonderful person who is frantically Googling “is straddling inappropriately flirting in a relationship” and landing on mine.
The answer to your Q is a resounding and all encompassing: YES.
If you are the straddler, either break up with your wo/man and get a grip on the individual whom you are straddling.
If your wo/man is doing the straddling on another’s lap, you need to please extricate yourself from this relationship ASAP. Also, get outside as it’s a beautiful day in Texas and you shouldn’t be stuck at your laptop wondering nonsense.