Kaidan was probably the closest they came to normality, but he's also typically beta, in line with gay stereotypes.
I think this is harsh on Kaidan. Shepard was literally Kaidan's superior officer. He is a bit reticent at times to offer his opinion because he's afraid of stepping over that line of command. I guess you can call that "beta," but "beta" is not usually a compliment, and I don't think this personality quirk of Kaidan's is a bad thing or makes him seem weak. He's definitely not weak. Keep in mind that he did actually stand up for someone he cared about, when the two were on equal footing (the girl from his school), and it sadly ended in disaster.
In ME2, he bitterly confronts Shepard; he certainly doesn't bow down to him or show him courtesy in any way shape or form. (p.s. This is actually one of my favorite scenes between Kaidan and a future-boyfriend-Shepard because it's just so painful; nothing Shepard says can defend him adequately from Kaidan's anger and disappointment.)
And in ME3, he again challenges Shepard. Then, once he's made a spectre, he and Shepard are finally equals; I honestly don't recall ANY moments of supplication or deference towards Shepard after that.
I personally don't like the terms "alpha" and "beta"; they're always applied to men, suggesting that to be "beta" is to be more "woman-like," which is seen as a bad thing (so there's a hint of unintentional misogyny there). I would describe Kaidan as quiet, thoughtful, intelligent, and principled. He will fight for what he believes in and he will stick by it.
Now if you're saying you want a loud, brash, "my way or the high way" (essentially a renegade Shepard) gay male love interest, then I agree we haven't seen that. But there's literally nothing, imo, about Kaidan that is a gay or bi stereotype!