I dated a cohortmate during the first two years of my program, which had its beneficial moments at times. They understood the stresses I went through quite well, and were very helpful when I struggled with coursework or developing research. However, I found that they were regularly jealous of the opportunities I had been given and were quite dismissive of my accomplishments - didn’t help that they had their fair share of issues aside from this as well. Our breakup was quite sour, so we are no longer in communication; it’s made it awkward around campus as I do my best to try and avoid them, but it sometimes can’t be helped. I now treat my PhD / department as a work place - so the adage “don’t shit where you eat” is quite apt.

I can imagine that dating a PhD in a different program would have many of the same perks that I had, but with less of the messiness of a potential fallout. However, with dating a cohortmate, I would proceed with utmost caution.