The redness shows may be you and your wife are having fungal infection.
It could also be that there is not much lubrication at sex.
Stimulation of her clitoral area can help her to get more lubrication
Next Steps
get examined by skin specialist, and avoid sex till you are well healed. Use lubricant that are water based at sex ir stimulat e her clitoral area for increased lubrication at sex
if needed use condoms ehile gavibg sex for few days till matters are resolved