This is what happens if you romanced Kaidan Alenko in the first Mass Effect, the romance option for Male Shepard & Kaidan is not available without modding/hacking, there are currently two ways of achieving it:
The first one is creating a female character on ME1 and change the gender of the character through the cheat console, wich can be activated editing the BIOInput file, you can find more details here: masseffect.wikia.com/wiki/PC_Tweaks
And the second way is editing your desired save with Gibbed's Mass Effect 2 save editor, but you need to get an updated version of it, one that has the ME2 Plot Table, otherwise you would have to edit and import the save for the changes to be aplied, the first step is loading your character, you have to chose the save that you want to edit, then you need to open the Plot tab, go to ME 2 Plot Table and the Flags tab, scroll down until you find the Romance options, you just need to click on 'Romanced Kaidan', then the next step is going to the Mass Effect 1 Table and select both 'Romanced someone' and 'Romanced Kaidan', the last step is go to the Values tab and edit the 'Player romanced Kaidan' option, you have to set progress value to 4, the only thing left is save the edited save, I highly recommend that you save the file with a different number than the original one you used for editing, that way you don't have to overwrite the save and you can keep it if anything goes wrong.
You can find the updated save editor here: social.bioware.com/project/4373/
Note: My character is a Soldier, I use the Mattock assault rifle, the Widow sniper rifle *, Claymore shotgun *, Phalanx pistol and the Arc Projector.
*It's possible to obtain the 3 Collector Base's weapons, you can get them through the save editor and editing the Colasced.ini to add a binding to unlock them, more information here: masseffect.wikia.com/wiki/PC_Tweaks_%28Mass_Effect_2%29
I sincerelly hope that you enjoy the video, and feel free to post a comment if you desire.
Mass Effect 2 and all it's features belong to Bioware and EA, I take no credit for this video.