Does Rosen Dean work for a boy? Our last name is Roberts. It would also honor both my middle name and my partners middle name. Rose and Dean. Our other two boys names are Hudson and Crew.
Rosen Dean Roberts is awesome!
Rosen Dean Roberts is too weird!I’m not yet sure. I like Rosen but it blends into Dean quite a lot - and sounds too me like Rosendeen. I might choose a different middle - eg Rosen Dempsey Roberts sounds better to me (not saying Dempsey is a winner just to show the rhythm is easier with a slower and longer middle).
Here are some ideas that I think could work with the other two boys and your last name, and still connect to Rose & Dean:
Roscoe Dean Roberts
Roscoe Deacon Roberts
Rowan Dean Roberts
Declan Rose Roberts
Ronan Dean Roberts
Rhodes xxxxx Roberts - you could use a new middle as Rhodes is a smoosh of Dean and Rose (and Dean doesn’t sound good after Rhodes).
Was going to suggest back to Roman but Roman Dean is a role/title - I wouldn’t use Dean after Roman either - if choose Roman, would use another honour middle name for your husband.
Hope this helps. 
not sure if this will bother you, but [name_m]Rosen[/name_m], [name_m]Dean[/name_m], and [name_m]Robert[/name_m] are all names that are heavily associated with the show Supernatural
[name_f]My[/name_f] first thought was no, because I assumed it was a girl name. However, I’m all for gender neutural/gender bending names and there’s absolutely nothing wrong with it. But my inclination would be to call him [name_f]Rose[/name_f] as a nickname, because it feels a lot more natural. I also think [name_m]Rosen[/name_m] feels significantly more feminine with your other boy’s names.
[name_f][/name_f]But the flow of the combo overall is lovely. I really like it with your last name!
[name_f][/name_f]How about:
[name_f][/name_f][name_m]Ross[/name_m] [name_m]Dean[/name_m] [name_m]Roberts[/name_m]
[name_f][/name_f][name_m]Roman[/name_m] [name_m]Dean[/name_m] [name_m]Roberts[/name_m]
[name_f][/name_f]and I strongly second @EloiseT[name_f][/name_f] 's suggestion of [name_m]Declan[/name_m] [name_f]Rose[/name_f] [name_m]Roberts[/name_m] (it’s so lovely)
Its too feminine in my opinion especially compared to his brothers names. I just forsee teasing in school & I don’t think a teenage boy or a man wants to be called [name_f]Rose[/name_f] or [name_f]Rosie[/name_f], which would definitely happen.
[name_f][/name_f]What about [name_m]Ross[/name_m]?