Well that computer can still be wired with your partner's computer wireless: both will work together perfectly fine.
Though it could be your cordless phone. These things operate on different channels (typically 1-11 or similar), so try and find out what channel your phone uses (may say in the manual), and if it's at for example 11, change the channel number for the router to 1 (furthest possible away). This channel number for your router can usually be found in the router settings somewhere, that 192.168.x.x stuff.
Also, if it's not so already, make sure the router's aerial is pointing upwards, since you're level with it.