Does anyone else love their partner but get only get really stressed and have meltdowns around them?

I love my boyfriend so much and he's very kind and supportive of me in all things. However, I always feel incredibly stressed out around him and have meltdowns when I'm alone with him or out in public with him. I do not have this problem when I'm alone or when I'm out with other people.

He doesn't do anything particularly stressing except for have his own schedule and emotions that I cannot control, and this lack of control on my part sends me into fight/flight/freeze etc.

My relationship-OCD tells me that the fact I usually feel terrible around him is a huge red flag and the relationship is destined to fail. But I think it's possible this is just an effect of being in burnout and spending time with someone I feel safe enough to express true emotion around.

I think it's possible I mask around other people, but can't mask around him? Sometimes I think I really want to mask though (to feel less self-conscious at a party or concert, for instance) and having him there makes me too self-aware of that masking to do so.

In addition to meltdowns, I also show little moments of genuine happiness around him and dance around him in ways I wouldn't with other people, so it seems he is a safe person to express positive and negative emotions around. Just wondering if anyone else has a similar contradictory experience with their partner?