Is there another way other than veneers and bonding/splinting to keep your two front teeth from moving?

Veneers do not splint teeth together, and if teeth or veneered teeth tend to space, then bonding them together with splinting fiber or an orthodontic wire is one way to keep them together, or else you could have two crowns made that are splinted together.The frenum may be a cause, but it could also be from your bite collapsing and your lower front teeth hitting the backs of the upper front teeth, spacing them apart.If you have a tendency to do this, then you might speak with your dentist or orthodontist about making you a retainer to wear EVERY NIGHT to keep your teeth from drifting apart.

The teeth continually shift over time unless they are retained in position by a fixed lingual retainer or a removeable retainer. Some stresses such as the frenum, short roots, or occlusion can further amplify movement of teeth even above normal shifting as you noted. Since you are prone to shifting, i recommend committing to wearing a removeable retainer for a minimum of 8 hours a day or consider a permanent retainer like a small bonded wire placed behind the teeth.