Well, to be fair, there's probably alot of other things that would complicate this. Being with Krem would mean that you were in a gay relationship. He fundamentally does not identify as a female. He acts and views himself as a male. Krem, if he were to be with you, would be identifying as a gay male specifically. There are a lot of nuances regarding gender in relationships where one partner is trans.
When it all works out, though, it's truly brilliant. My husband and I have a 'couple-friend' where one partner is a bisexual transman (like Krem) and the other is a bisexual woman. Gender and sexuality are just such a non-issue for their own worldviews that it's amazing to me to watch. It then reminds me how hung up on gender identity I can be, even as a gay guy.
I love that characters like Krem can introduce conversations like this to the community.
I suppose he would be identifying as a gay man (as someone who views themselves as a man and is attracted to people with male genitalia). I would still consider myself heterosexual for being attracted to him as he is female. I don't want to personally consider him as "acting as a male" because, personally, I don't think such a definition should exist. He's acting as would stereotypically be seen as "masculine", but really I'd call it just another set of behaviors. I want to see that as being unrelated to sex, but I get that most people see it as being directly related. I totally understand that he views himself as a man, but that doesn't make him male (biologically). He would still be a female who likes males (even if he's a man… if that makes any sense). If two females see themselves as men and are in relationship, I guess they'd be gay men (albeit gay men who like being with people who have female genitalia? I'm quite confused at this point), but then what makes them different than two butch lesbians in a relationship, but nouns/pronouns? I'd say nothing, but either way I'd respect their wishes with regards to how they wish to be viewed. Idk, maybe it's more nuanced than I think.
It definitely is nice to hear of your friends being in a happy relationship that falls outside the norms of society. I don't like the idea of gender identity at all, although, I do fit the "masculine" stereotype, I guess. Anyways, I have male genitalia and feel attracted to people with female genitalia (and therefore consider myself heterosexual), but I like them more when they dress in a stereotypically "masculine" or "butch" manner: that is to say suits & ties, baggy jeans, t-shirts, hoodies, sneakers, boots, short hair etc. I know women like that are rare, but I can dream that I'll find someone like that that I click with.
It's probably best that I avoid such relations, but that doesn't stop me from admiring the appearance of some pre-op f2m trans-people. Anyways, I'm just going to say I respect these people and want to respect how they wish to be viewed, but I think it'd get too confusing were I to actually get involved with someone of this type.