That's understandable, actually. It very well could be related to the Reta. There are several reasons why this might be happening.
Many people on GLP-1s or similar meds report a lower sex drive. This is often connected to how the medication impacts your hunger, energy, and even your mood.
Even when you're just maintaining, your calorie intake is probably lower than before. This can lead to fatigue as your body adjusts to fewer calories. When you restrict calories, your body conserves energy, which can decrease libido.
Reta can also cause emotional blunting or a lack of motivation for some, because it affects the brain's reward pathways. Activities or things that used to excite you might not feel as enjoyable anymore. GLP-1 signaling has been shown to have effects on the brain's reward and motivation centers, which can explain why some people experience decreased motivation or feel emotionally 'blah'.
Furthermore, losing weight and eating less can change hormone levels, like estrogen and testosterone, which also play a role in sex drive.
So, while a decreased sex drive might not be a listed side effect, the combined effects of low energy, calorie deficits, hormonal changes, and emotional flatness could definitely be contributing factors.