I think the definition of what unconditional love really means is important to look at. To many that equates to an almost an unchanging level of love and positive regard for someone no matter what it is they are doing, have done or will do in the future. Honestly its a pretty unrealistic expectation and fairly foolish.
People, situations and everything changes. I think that one can still have genuine concern, interest and even some measure of love in the face of many issues, but that is not to say that they may or may not love them less. Kind of like that old cliche, "I love with them, I'm just not in love with them".
As a therapist I see a lot of people struggle with not loving their parents and feeling guilty or ashamed, or struggling because they still love their parents (to some extent) even though they may be toxic to one another. My belief in that is that you really can't control who in your life you are attracted to or have concern for so its better to get an understanding of some of the "whys" involved and help to normalize the conflict and to figure out what is the healthiest balance for the client. Its not uncommon to have a conflicting approach and avoidance feelings with those we "should" consider loved ones.