There's actually quite a lot of academic work on homosocial behaviours - intense same-gender friendships that can be very close and affectionate. It's definitely a normal part of human experience that is very important to us, and our mental health suffers when we don't have close, affectionate friendships. In the UK, US and Canada, a lot of mental health campaigns aimed at men focus on getting men to nurture these friendships and to open up to their friends.
Unfortunately we can't ask animals whether they feel intense affection, romantic love, sexual attraction... and, indeed, creating these distinctions between different kinds of love is a human thing. What we do know is that animals do court, mate and rear young with others of the same sex, and that this is widely documented across species. We also know that animals don't necessarily raise families within a monogamous pair-bond: we know that some species raise young communally in a creche, that some take many mates (female eclectus parrots for example), that some form stable triad relationships. We know that some species of fish even change gender as they mature or as the shoal dynamic shifts, like clownfish and parrotfish.
We've done animals a great disservice by projecting human values - themselves a product of a particular time and culture - onto them. It's stopped us recognising all sorts of interesting, important behaviours and from fully appreciating the great diversity found in nature.