Like, what would make a man need testosterone? I’m having trouble understanding....

My fiancé and I have been together almost 4 years...typical story🙄sex used to be amazing and constant and now....far and few between!

It’s caused so many issues. Everytime I mention it, he makes some new excuse. The newest one being, that when we argue I make him feel imasculated and then “expect him to be so sexually motivated”....

Where I have trouble understanding is because when we have sex, once every 2-3 weeks sometimes once a month, he performs fine. No trouble getting hard or getting off. Now, if God forbid I try to initiate sex two days in row I’ve noticed the second day sex feels different, like it feels like his dick isn’t all the way hard, but he still reached climax, just makes me feel like he’s not as into it as me and makes me feel insecure. If he’s drinking, he will get feeling frisky and want sex but still. He works 12 hour shifts 4-5 days a week and always tells me he can’t have sex on work nights because it “takes his soul and then he can’t wake up in the morning”....feels like excuses. I’m pregnant and the horniest I’ve been in my whole life it seems like and he’s making me feel like shit. I truly don’t believe he’s cheating or anything, if he’s not at work he’s with me. But I have caught him watching porn occasionally. I’m so lost. Like how can you watch sex and shit but hardly ever want it with me. I asked about testosterone because twice now I’ve seen him researching it online. Just the other day I saw “liquid testosterone” on our computer search.....

Like do y’all think something is wrong and he’s just uncomfortable talking to me about it or do you think it really is just this vicious cycle of me feeling insecure and lashing out, and in turn him feeling imasculated. I thought for a man to need testosterone he couldn’t perform at all???? Pleaaaaase help me out with some answers.