Rick doesn't know when to quit
We know that, despite being the leader of the group, Rick isn't the most emotionally stable survivor of the zombie apocalypse; after all, he flat-out hallucinated his dead wife Lori for parts of season 3. But it wasn't until he entered the relatively safe confines of Alexandria that he became really paranoid.
He assesses Alexandria not as a safe haven but as a place where they may become weak. In a jaw-dropping moment, he suggests to Carol and Daryl that they may have to take Alexandria over. Then, he openly flirts with Jessie, a married woman. When he sees her husband, Pete, from a distance, he reaches for his gun, but doesn't draw it. To cap it off, he beats Pete into a pulp. Yup, Rick has mutated into season 2 foe and former best friend Shane.
Lucky for us, he redeems himself with a nice speech — until he's interrupted by a murderous Pete.