People express themselves differently in various forms of communication. Liking pictures on Facebook could be a low-effort way for someone, like your ex, to show interest or maintain a connection without engaging in more direct communication. However, this doesn't necessarily indicate a desire to rekindle a relationship.
The lack of texting might be due to personal preferences or circumstances. They could be more comfortable with online interactions, or it could be a reflection of their current lifestyle. It's essential not to jump to conclusions and consider that everyone has different communication styles.
If you're interested in understanding their intentions better, a polite and casual message could be a way to initiate a conversation. However, be prepared for various responses, and respect their boundaries if they choose not to engage further.