Jean knows he should make sure Reiner loses the sight of him. That he would continue believing that was just a figment of his imagination. They needed to avoid possible conflict and problems. Their meeting - Reiner confirming it was really Jean - would be problematic.

Yet his mind goes back to Shiganshina. The desperate plea to Hange to not kill Reiner. Something he struggled to understand for a while. It took several days, even weeks, for him to finallyt understand that he still cared way too much about him. Still did.

The decision he makes is done with his heart, not with his mind. The decision to enter an alleyway that was away from prying eyes and ears. The decision to make sure Reiner saw where he was going. It was up to the other man if he'd take the chance or leave.

At least if this lead to trouble he'd only drag himself down. Reiner wouldn't learn about anyone else being there. Not if Jean could help it.