Testosterone is not the only thing that can be at play healthwise, other hormones and nutritional deficiencies, among other things, can affect libido and sexual function.
My sex drive has fluctuated, but generally on the lower side especially as I've gotten older. Sometimes that has been due to health issues I've described above. Other times it's hard to say. I've read around the topic a bit and asked my far higher sex drive spouse his opinion. This only works really if you're both open and up for it (pun not originally intended, but let's go with it).
His advice was: be patient, but not subtle. Patience and communication is key. Like others said, you can't really make someone horny. Bodies are complicated and assumptions can cause problems. We sometimes fall into ruts because I don't think he's interested or serious for reasons and he doesn't think I am due to my libido & neither of us wants to pressure the other. This plus my libido has what I call inertia issues. I've read and heard more technical terms, but it's the easiest way for me to explain it. I often remain at rest & could not care less until intimacy already gets beyond a certain point to move my brain to remembers that this can be more fun than work or watching TV. I can be perfectly happy without it, but I'd be just as if not more happier with the right nudges along the way, I just don't tend to think about it.
So, my DH has to communicate his interest because, for some reason even after many years knowing this, I'm prone to doubting his interest or think he's joking, so he sometimes needs to do this as bluntly as 'yes, I'd like sex if you do' and I have to communicate both when I'm am actively interested and when I am open to trying even if we both know the switch from rest might not happen or I might end up with a flare-up that is a real mood killer. Sometimes it's with words, sometimes its signals like in the winter I would turn the heater on in our room.
Another idea, brought on by my health issues meaning my body is not reliable - what is great one day can be painful the next - is, this feels a bit silly typing out, but having a list of things to try and having games that come up with ideas. Due to the above issues, I often don't know where to start and overthink it (what if it does wrong, what if my body doesn't cooperate, and so on) so picking off of a premade list or playing a game like - I've forgotten the title of, but it can be found on LoveHoney, it looks and works like connect 4 except the pieces have ideas on them. Some of the ideas are just fun like "naked pillow fight". There are plenty of other that are similar for coming up with ideas but that one works well for us. It takes some of the negative tension and pressure off of things which, as the low libido partner, can be an issue. Sometimes it's suggesting a game or very blunt "I'm going to shower and masturbate, do you want to join me or watch?" to get out of the inertia.
All of these do require both people's cooperation, interest, patience, and communication. As others said, I would ensure at the very least you have enough in place so you're not feeling down about it before marriage which is certainly not going to help on its own. Yes, it is not everything, but if having a low-libido partner is getting you down and you're having doubts, then something should be discussed and done.