*clears throat, pushes up glasses*
If you included some variation of the vulcan mating urge known as pon farr, they'd actually fit into TiTS rather well. Every seven years after reaching sexual maturity, vulcans are consumed with an overpowering need to mate, one that, if not satisfied, will literally kill them. They experience intense mood swings and bouts of psychosis, and require satisfaction on a both a physical (through some very angry sex) and mental (through telepathic bonding and meditation) level.
So if you made TiTS vulcans experience something similar at a slightly increased rate, say once a year or once every few months like a more traditional "heat" or "rut," you could include them fairly easily. Also, vulcans still have sex when not experiencing pon farr. Love was probably the single most explored aspect of the vulcan "emotional suppression" over the various different Star Trek series, and the general consensus is that vulcans still feel love and attraction to some extent. Enough that they engage in romantic relationships and activities of their own volition fairly regularly
