Sometimes relationships are hard and feel one sided. Maybe your partner isn't a fan of couples therapy (maybe even individual therapy) and you feel alone and frustrated. You can give an ultimatum (I dont recommend this) and force the person to go to couples therapy but does that really ever work out well? You can just give up but that doesn't sit right with you because you love them and can see there are solutions to your issues.
Individual therapy can address relationship concerns by working on your personal issues and dynamics, which can often interfere with our relationships.