Based strictly on visual observation of the photos without any EXIF data, my eyes see a combination of the following issues:

• Most of the shots are slightly front-focused. That means the area of sharpest focus is slightly in front of your subjects' faces and eyes. Try manually selecting a single focus point instead of allowing the AF system to select one from all of the points, as that usually results in the nearest object being in focus. If you are already using a single focus point and centering it on your subjects eyes, then the lens and camera need to be calibrated to each other. Unfortunately, your T5i does not have the capability to correct the problem using Auto Focus Micro Adjustment. The lens and body would need a trip to a Canon Service Center to be adjusted. If both are still under warranty, this adjustment should be covered.
• The edges and corners show a moderate amount of Chromatic Aberration. This is to be expected with the EF-S 18-135mm f/3.5-5.6. It is part of the price you pay for a wide focal length range in a single, inexpensive, lightweight lens. If you save your images as RAW files, you can apply correction profiles for that lens using Canon's Digital Photo Professional software that was included with your camera. Other RAW convertors, such as Adobe Camera Raw or DxO Optics may also include profiles for your camera/lens combination.
• The harsh Bokeh associated with a seven-bladed diaphragm. The fewer blades an aperture diaphragm has, the less circular the aperture will be and the rougher the bokeh will appear. Most premium lenses use 8, 9, or even more blades to smooth out the bokeh.
• Some of the shots may demonstrate minor diffraction issues. The 4.3µm pixel pitch of the T5i means the diffraction limited aperture (DLA), or the point at which diffraction begins to affect image sharpness, is at f/6.8. To avoid diffraction, use an aperture wider than f/6.8.

All of these things appear to be combining to one degree or another to create the bluriness you are seeing. The hard bokeh makes the slighlty out of focus faces look worse. If you stop down to increase the DoF, you also make the diaphragm less circular, which makes the bokeh even harsher and introduces diffraction if you go above f/6.8. Other than the front-focus issue, the pictures are about what I would expect from that lens.