Pip and Seras; and Alucard and Integra are not "opt-out" pairings in the manga. You cannot have the characters and their conclusions without their relationship which is, partially, romantic.
When Hirano decided to write Hellsing, one of the earliest things he decided on was the couples (those two, btw). He elaborated that when he answered about Pip and Seras specificially, and in their case, the entire Seras' character arc about her becoming a vampire accepting to drink blood did not even exist until he decided to bring in Pip (recycled from an old manga of his) and stick them together.
If you have any reading comprehension, you know Pip was meant to be more than a greedy mercenary, and he was bummed about it as a kid he had to follow his family's steps. It was through his relationship with Seras, we learn he's actually got a heart of gold who can't forgive the nazi vampires for killing innocents. We know he's a true hero. Hirano didn't need to spoonfeed this because he was blatantly written that way. His arc and Seras' feed each other and reach that conclusion: together forever as a combination.
Now for the other couple Hirano singled out: Alucard and Integra. Is it not obvious?
(Not to the ones who wishes Alucard or Integra were fucking their self insert or their pet fanship!)
The entire manga you have repeated Alucard lost everything he had in wars he waged, this flashback of that reduced him to tears. A concern of being a monster is sacrificing that for war, but the whole point is that Alucard is suicidal because he doesn't want to lose things again. He's full of regrets. This doesn't mean he wants to die, he's just in denial and suffering PTSD and prefers to die before it happens. What did he lose? His subjects, his country, his castle, twice. But most importantly, he lost the love of the one he was fighting for.
As Vlad, he fought out of religious devotion. For God. As Dracula, he fought out of romantic devotion. For Mina.
Both God and Mina abandoned him. They didn't love him. That revelation, in that dawn of war, made him give up and surrender to despair. Vlad became Dracula. Dracula became Alucard. All the manga had him piecing his past loss and coming to terms with it, but it's not just accepting, but realizing now he has the love he sought twice in Integra. Integra is the Master, the lady liege to his blood knight (even literally stated since their meeting). The figure of a maiden leading a knight is symbolically both a religious and romantic figure.
Integra's arc in the manga was struggling with two things: the nature of monsters (which Alucard and Seras aren't, in her conclusion), and her role as leader. She's the one who understood Alucard without even trying. She understood and valued him. The steel she gained, the wisdom, all was interconnected to Alucard's arc like Pip's and Seras' were for each other. Because Hirano needed her to accept him. Not just that but he needed her to become the compass Alucard needed to act.
In the final dawn, he finally recalls everything wide awake (no longer creeping in dreams) while he disappears staring another dawn, integra calls out for him to stay. He smiles, unlike the times he cried and mourned for his loss. Integra is the reason why Alucard stays/fights, according to Major in the earlier volumes. But he didn't figure out how meaningful that was. He also mentions a play that's repeating itself again, the one played a century ago (when Dracula fought to claim Mina). Which is supported by the neutral narration of the text when Alucard returns to London and proceeds to ignore everyone to greet Integra (a recurrent thing). He who is a battle junkie, ignores the war and goes to Integra, leaving his troops, taking care of that. Even after Captain kicked him.
Following now? Alucard wanted Integra like he wanted Mina (that's why there's a clear parallel of history repeating again stated twice about this); he's also devoted to her as he was to God. His relationship with Integra satisfies the dual loss he experiences as Vlad and Dracula. Integra returns his feelings. That's the point. Or he would have lost. He would have wept instead of smiling. She wouldn't have waited for him (the most romantic Japanese archetype of all time) to see him again in great anxiety. Trying to remove the romantic or religious devotion elements of their relationship makes their arcs fall apart (specifically speaking: the parallelism with his war and motivation 100 years ago was brought up twice in text! In neutral narration overlapping the past and present: "a vampire came to London to claim a woman he desires"). If Integra hadn't return both things to Alucard, Alucard would have stayed dead. He would have changed his name and identity. It would be a bad end. It would also mean Integra failed her arc too.
It's the most plain case of third time is the charm. But for it to be whole, it has to be both things, and the romantic one is literally made text instead of subtext as the religious one.
You cannot ignore this if you claim to like the characters, or overlook one. Like you cannot ignore how Pip and Seras compliment each others in a fucking literal sense. Their couplings weren't optional. It was the DNA of their entire characterization in the manga whether you like it or not. They are not pairings that just happened as bonus, or were tack on, they were basically necessarily for the four characters to develop this way.
