Well technically there has been relationships where even with birth control, medications of any sort that alter your mind can have effects. For example many women who take birth control lose sexual desires towards there significant other after they hop off whatever they are taking. So it’s a bit much but also reasonable
Hate me if you must but I honestly don’t see that as a red flag. He’s not the best guy, but a normal guy. Best guy will either word it differently or show commitment regardless of your mental status. Atleast he’s not saying he will break up with you. Don’t take it personally, but nobody in their right mind would want to have somebody with a mental condition. I’ve been through self-harm and suicidal tendencies, but I myself wouldn’t want to marry someone who depends on anti-depressants.
If it’s somebody I already love, I’d do anything to encourage them to break out of that. And I think that’s what he is doing, although he made it a bit too manipulative. But, I don’t think you need to be with a guy who words things like that. Make sure you show him that you know how to love yourself. It’s not his fault he might come off that way, but you should gain control and let them know you’re not just somebody ‘waiting’ to get proposed to. You deserve better.